Delete podfile.lock and manifest.lock, then re-run podfile install, then continue from there using the "easy" configure app from Fabric.
There are some very nice screen-shot slide-show demos on Fabric.io's site. I found them with Google - don't see where they are accessible from the site.
FYI, if you're having issues, it's not you :). Basically (as of August 3rd), every step of the Fabric onboard process is potentially broken.
- If you're lucky, you might have no issues.
- If you're not, :( you might have issues to resolve at every step, including signing up for the service which can put you in an endless sign-up loop, and so on from there.
Hopefully these will all get fixed soon.
Warning: most of the answers you will find via a search will be outdated, because apparently fabric.io changed a lot on July 15th, but if you scroll down anything you find on stack/o, you might find a newer answer.