Workmail User can't connect to Workdocs

I recently signed up for both Amazon Workdocs and Amazon Workmail, however when I attempt to attach a document from Workdocs to an email I receive an error:

"It appears you have not been enabled for WorkDocs. Contact your IT Administrator for more information." (image attached)

I am the only user and administrator. Both are in the same region and since I just started using both services it should not be related to space requirements.

I've tried searching for a solution, but most of the results appear to be geared toward an actual Active Directory, and I chose Simple AD. So, I'm not sure how to fix the problem. Any help appreciated.