I can not contact the previous owner

Here is Apple’s support documentation that describes Activation Lock and the methods 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, if a device is Activation Locked by an AppleID that you do not control, you must secure the assistance of the account owner to deactivate the Lock. Without their assistance, you’ll not be able to defeat or otherwise bypass the lock.

If you have original documentation (that includes the device serial number) that proves ownership, Apple might be prepared to assist with reset/wipe of the device to a usable state. Otherwise, Apple will not assist - and nobody here will will be able to help.

they could yes

https://getsupport.apple.com/

and or https://www.apple.com/retail/geniusbar/

the lock is not on the iPad but on apples servers the previous owner needs to do the following to remove the activation theft protection What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

Turn off Activation Lock - Apple Support

https://iforgot.apple.com/password/verify/appleid