With a lot of the mobile stuff we were stuck doing full page cause the technique we used involving post message in JS ended up failing.
Can you elaborate a bit about the process after you click associate? Does it redirect to key base and then redirect back to us?
If there is a redirect chain involved you are going to need a new route here with a new full page. If this is simply making a call to the discourse server and it takes care of the magic, then you can get away with a modal.