If your device is Activation Locked, this help page will provide most of the information that you’ll need:
https://support.apple.com/en-us/HT201365
If you have forgotten your AppleID or associated password, these can be recovered here:
https://iforgot.apple.com
To recover your credentials, you’ll need access to one of the following:
- Your primary email address mailbox that corresponds with your AppleID
- Any of the secondary/recovery email addresses that should be configured for your AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your AppleID
Unless you AppleID account has not been fully/correctly configured, or has been seriously neglected, recovery of the AppleID and password should not be difficult.
More information about recovery of your AppleID:
https://support.apple.com/en-us/HT201354
More information about recovery of your AppleID password:
https://support.apple.com/en-us/HT201487
When you recover access to your credentials, you would be well advised to log-in to your AppleID account from a web browser - and verify/update any email addresses and trusted telephone numbers:
https://appleid.apple.com
When you recover access, you can change/update your primary email address that is used to log-in to your AppleID account. More information of changing details here:
https://support.apple.com/en-us/HT202667
https://support.apple.com/en-us/HT204071
All of the above assumes that you are the original owner of the iPad with which you are having difficulty. If the iPad was previously owned - and not correctly prepared for use by a new owner - then the Activation Lock may be associated with an AppleID that you neither own nor have control. In this situation, you have no alternative other than to secure the cooperation of the previous owner to whom the AppleID that is currently associated with the lock.
If the username “hint” is nothing that you recognise, you will likely have a problem.
I hope this information and resources prove to be helpful in resolving your problem. Do let us know how you get on.