Hi Niggstroyer69,
We understand you'd like to activate iMessage on an iPad. We're happy to help.
So based on the images you included it looks like you're trying to turn on the Messages in iCloud service , but have not yet activated iMessage. You'll need to activate iMessage first before you can start using the Messages in iCloud service.
To start, navigate to Settings > your name at the top > iCloud, and turn off the Messages option.
Then go to Settings > Messages and sign in to your Apple ID account. If you would like to use the Messages in iCloud service, you'll want to make sure to sign in to the same Apple ID account you're using for iCloud.
Once you have signed in and activated the iMessage service, you can go back to Settings > your name at the top > iCloud, and turn on the Messages option if you'd like to use the Messages in iCloud service.
Set up Messages on iPad
We hope this helps. Cheers!