Hi

ifueko2468 Said:

"Hi: Bought an iPhone6 plus from someone and am trying to activate it but it reads that below"

-------

Try this Site: If you can't Activate your iPhone - Apple Support

As a Last Resort - Return it.

You should do what the message says.

Either try again at a later time or contact Apple Support to check about the message or confirm if there is a service downtime.

Just FYI, the iPhone 6 plus is a very old model and can't run the latest iOS which is required for most apps now. You may want to think about returning it and getting your money back.