Please report the issue by clicking on the Click to report issue link in the installer (see the yellow bar at the top).
This will ask you for some details and logs and sends an email directly to our Development Team, who are working hard to find and fix the issue as soon as possible.
This will also open a support ticket with our Support Team, we will keep the ticket open until the issue has been resolved and we will update you by email of any progress.
In the meantime, please find other methods of installation here - https://emailsignaturerescue.com/support/all-supported-software
We apologize for the inconvenience, the app is still in Beta and we're trying hard to resolve these issues for everyone. This is a top priority for us, however since it's only happening for a small number of users, the issue is hard to identify.