If your iPad is disabled, or you have forgotten your iPad passcode, you’ll need to follow this process:
https://support.apple.com/en-gb/HT211078
You’ll need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS).
Should it be encountered, here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:
https://support.apple.com/en-us/HT201365
https://support.apple.com/en-gb/HT201441
As you will discover, unless you are the owner of the AppleID that was last used to activate the device, or unless you can secure the cooperation of the previous owner, you’ll not be able to defeat or bypass the Activation Lock. Without documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple won’t assist - and nobody here will be able to help you.
If you are the owner of the AppleID that previously activated the device - and 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 to the iPad, you might be well advised to set-up properly with an AppleID that belongs to the actual user of the device. AppleID sharing should be avoided - as sharing an AppleID account risks all manner of issues including difficulties with account security and leakage of sensitive and personal data. Here is the procedure that you should follow to properly prepare the iPad for a new user:
What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support
I hope this information and comprehensive guidance proves to be helpful in resolving your difficulties.