Simple WA which checks if someone downloaded your Weakaura or not.
Just get this Weakaura put it inside the pack you want to upload for your guild and change the Custom Options.
Supports 2 Person who can start the check and receive the whisper.
If there are any suggestion what else would be needed just leave a comment.
Also check the Loading conditions for the type of content where the check need to be loaded, like raid or something else.