Here are the Apple support pages that outline the Activation Lock - and the available mechanisms by which it can be satisfied:
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
Turn off Activation Lock – Apple Support
As you will discover, unless you are the owner of the AppleID that was last used to activate the device, you’ll not be able to defeat or bypass the Activation Lock. With documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple may be prepared to assist - otherwise they and nobody here will be able to help you.
If you have the necessary documentation, Apple have introduced a portal though which you may be able to request release of an Activation Lock:
How to remove Activation Lock - Apple Support & start an Activation Lock support request.
If you are experiencing difficulties with (re)activation of your iPad, you may have more success if you connect your iPad to a Windows PC (with iTunes for Windows installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS). Once connected to your computer, your iPad will be detected - and you should be able to activate using iTunes.
- Make sure that you have the latest version of macOS or the latest version of iTunes.
- Check that your computer has an Internet connection.
- With the cable that came with your iPad, connect your iPad to your computer. Locate your device on your computer.
- Wait while your computer detects and activates your iPad:
- If you see an alert that shows "Set up as New" or "Restore from Backup", it means your iPad is activated.
- If you get an error message that says the "activation information was invalid" or "activation information could not be obtained from the device", use recovery mode to restore your iPhone.
A restart of your WiFi Router and/or a change of DNS settings may also be helpful.
To restart you home router, disconnect power - then wait at least 30 seconds before restarting. When you router has rebooted (which may take several minutes), force-restart your iPad:
- On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

- On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

For recommended DNS servers (configured at your home router and/or your iPad), you might choose one of the following Recursive DNS Providers (IPv4 and IPv6 addresses included below):
Quad9
9.9.9.9
149.112.112.112
2620:fe::fe
2620:fe::9
OpenDNS
208.67.222.222
208.67.220.220
2620:0:ccc::2
2620:0:ccd::2
Cloudflare
1.1.1.1
1.0.0.1
2606:4700:4700::1111
2606:4700:4700::1001
Should it be necessary to escalate your issue to Apple Support, the quickest route to engaging with Apple Support will be via the Support link at top-right or bottom-left of this page.