If your iPad has been used to create “many” new AppleIDs, this is the source of your problem.
From recollection, an individual device can be used to create only three (possibly five) AppleID accounts. This limitation is hard-coded in Apple’s back-end server infrastructure - and cannot be bypassed by the device. You can create another AppleID account, but not from a device that has already used its allocation.
This measure is intended to prevent account abuse.
How to create a new Apple ID – Apple Support
If you still need assistance, having followed the link to create a new AppleID, you might be best advised to contact Apple Support. The link to Get Support is at top-right of this page.