My iPad could not be activation server is temporarily unavailable

You should check this article: If you can't activate your iPad - Apple Support. https://support.apple.com/en-us/HT201407

If your iPad is a cellular model, some have reported that temporarily removing the sim allows activation to complete.

Otherwise, 5 possible causes for that error message:

1] Activation server is actually down. Very rare occurrence, and of short duration when it

does happen. Solution - try again.

2] Your firewall and/or antivirus software are preventing the necessary connection. Solution -

temporarily disable your firewall and/or antivirus software until the activation completes.

3] computer being used for activation has been used to jailbreak an iOS device in the past.

Solution - use a different computer.

4] iPad has been jailbroken. Your favorite search engine may provide some direction, but jailbreaks often prevent

activations/updates from succeeding. Per Terms of Use for this forum, discussion of jailbroken iPads is

prohibited.

5] your region and/or timezone settings are inconsistent with your actual location. Solution - set region and/or timezone correctly.