Why does my IPad always ask for the ITunes and IPad password but will not accept it. Also it shows "a problem has repeatedly occurred on Apple ID

Apple id is your email address and password which you used to set up itunes. You will need these to activate your ipad. If it is a new ipad you will need to open an itunes account. If you are a second user you will need the user name and password that was used to set up the ipad originally.

Try hooking your iPad up to iTunes on your computer and perform a factory reset, changing the username and password.

Under this circumstance you may have to reset the iPad if you forget both Apple ID and its password.

To reset iPad without Apple ID, you need first put iPad into DFU mode and connect it to your iTunes. Your iTunes will help you to reset your iPad without entering Apple ID easily. Resetting your iPad with this method will result in wiping all the data in your tablet. The following steps will show you how to do that.

Step 1: Open iTunes on your computer and connect your iPad to the computer with a USB cable.
Step 2: After that, turn off you device. Press and hold the Home button for 3 seconds.
Step 3: Put your iPad into DFU mode: Press and hold the Power and Home button for 10 seconds. Then release the power button and keep holding the home button. When you see the Apple logo disappears, you have successfully put your iPad into DFU mode.
Step 4: When iTunes detects that your iPad is in recovery mode, you can restore it now.
Step 5: Click on Restore iPad. Then you will be notified after the reset and your iPad will take a restart.

After resetting your iPad with the guidance mentioned above, you'd better create a new Apple ID and password in time. After resetting iPad, you will get all the data swept from iPad, and you can restore the files from your iPad, iTunes backup or iCloud backup. However, you can't backup iPad to iTunes/iCloud without Apple ID before you reset your iPad . In this case, you need the third-party iOS data recovery software to help you recover lost data from iPad after factory reset without Apple ID.

http://www.leawo.org/tutorial/how-to-reset-iphone-without-apple-id.html

Generally speaking, you need the Apple ID to reset your iPad. iPad needs you to enter the Apple ID to switch off your account and the Find My iPhone service will be turn off. If you are using iTunes to reset your iPad, you need to enter the Apple ID when your iPad reboots.

But if you have no Apple ID or passcode, you will have to reset your iPad without Apple ID. To reset iPad without Apple ID, you need first put iPad into DFU mode and connect it to your iTunes. Your iTunes will help you to reset your iPad without entering Apple ID easily. Resetting your iPad with this method will result in wiping all the data in your iPad. The following steps will show you how to do that.

Step 1: Open iTunes on your computer and connect your iPad to the computer with a USB cable.
Step 2: After that, turn off you device. Press and hold the Home button for 3 seconds.
Step 3: Put your iPad into DFU mode: Press and hold the Power and Home button for 10 seconds. Then release the power button and keep holding the home button. When you see the Apple logo disappears, you have successfully put your iPad into DFU mode.
Step 4: When iTunes detects that your iPad is in recovery mode, you can restore it now.
Step 5: Click on Restore iPad. Then you will be notified after the reset and your iPad will take a restart.

After resetting your iPad with the guidance mentioned above, you'd better create a new Apple ID and password in time. After resetting iPad, you will get all the data swept from iPad, and you can restore the files from your iPad, iTunes backup or iCloud backup. However, you can't backup iPad to iTunes/iCloud without Apple ID before you reset your iPad. In this case, you need the third-party iOS data recovery software to help you recover lost data from iPad after factory reset without Apple ID.

http://www.leawo.org/tutorial/how-to-reset-iphone-without-apple-id.html

How well do you know the person that you bought it from?
Provided it is not stolen you might be able to have an authorized sales rep help you.

Follow these steps to reset your forgotten Apple ID password: https://support.apple.com/zh-cn/HT5787

You don't need to know your password for the iPad. As long as you know the password for your iTunes account, you used to setup the account on the iPad for. Connect the iPad with the computer and open iTunes and give in the password for the iTunes account. Apple will unlock the iPad and you can setup a new pass code for the iPad.
When you forgot your iTunes password, you have to contact Apple and prove you are the legal owner of the account.
Use this link to find more support for that:
Apple ID Support

You have setup an iTunes account with Apple. When you connect the iPad to iTunes, (WiFi or via computer) they ask you the password for your iTunes account. If you forgot that one, Apple can send you an reset code to the mail address connected to the Apple account. (Not the iCloud mail)
If nothing works, goto the closest Apple store and take your invoice with you and an ID card, to prove you are the legal owner, perhaps they can help you.

Can you log in from another PC and change profile settings?

Have you ever synced your iPad in iTunes? If this is the situation, there are many postings on Apple and other sites to restore your iPad and password.
If you have never synced your iPad in iTunes, you will have to take it to an Apple Store or send it to Apple to be restored...