Error 6 when trying to sync first time only on some ipads

[Jesdamian]

Were beta testing and I have 8 users

 

I use mirror sync 1.5 build 5937 to create a link to the offline database.

 

I then email all users the link.

 

About half of the users can download the file, open it in filemaker go, but when trying to sync, they get an Error 6 

 

Error 6 apparently means the file is read only. But if I had a configuration error in the server, wouldnt all 8 ipads fail?

 

 

edit: we have 10 licenses available so its not a license issue

On the ipads with issues, I've deleted the offline version from their system and attempted to redownload it using the same link, same issue. I even restarted the ipad to try and clean the file system