I re-read one of the pages you linked and the solution was stupidly simple. This is a kindle, it's not able to run all the google services I tried setting up (I'm tied to a google apps domain). So I went into the Meraki users dashboard and made a new meraki user. I signed in with that account and was able to add my Fire. Which means I'll be able to add the other one later. Thanks for pointing me in the right direction!
... View more