Snapshot Settings page not working

I network activated the Snapshot plugin, and when I try to access the Settings page, I get the following error:

The website encountered an error while retrieving https://solofirm.net/wp-admin/network/admin.php?page=snapshots_settings_panel. It may be down for maintenance or configured incorrectly.

Here are some suggestions:

Reload this webpage later.

HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

Any idea what the problem could be?