Import format for Protected Content

I'm trying to use the Import function in Protected Content so I can upload members from my previous plugin (wp eMember), but I keep getting a message saying , "No valid export file uploaded, please try again."

I've tried .CSV, .XLS, .XLSX, and .XML formats. Since you have no user manual yet for Protected Content, I am completely at a loss. Please give instructions on how to make this work.

And when will the manual be ready? It seems we should have some better documentation by this point.

Thank you,