If Tot isn't starting at login, or if the switch in the app settings is disabled, it's because Tot's not allowed to run in the background.

To get things working, go to System Settings > General > Login Items & Extensions and find "Allow in the Background". Tot should be in that list, and make sure that it's switched on.

The next time you click on "Start Tot at login" you should see this security warning appear:

This message, which we can't change, is misleading. Tot doesn't do any background processing - it only launches the app when you login.

If you turn off "Allow in the Background" in the future, you will have to go through these steps again.