I'm having the problem, too.
The problem is "Error: file not found" problem when clicking a link to a protected file (when loggged in as administrator).
I'm starting a new site and didn't create the protected posts/files until after I installed UAM.
I've tried -
o Moving my uploads directory from wp/../uploads to the default "wp/wp-content/uploads and making corresponding change to
o Turning off "extra web security" on the domain hosted at Dreamhost (thinking that might affect the "safe mode" setting)
o Changing to "normal" from "fopen"
I opened a new browser session to test after each change, and nothing seemed to help.
And now, I seem to have broken things so that a user other than the admin who *is* in the authorized group can no longer see a protected post, let alone the protected file. [The admin can still see the post, but still gets the "file not found".]
I'll go back and double check -- and probably reinstall -- but just thought I'd add some support to those having the problem.
http://wordpress.org/support/topic/253361?replies=6 ended without a full discussion of how the "safe mode" might be resolved.