Subscriber role only?

Hi! I use your plugin because of invitations function. I’ve noticed that new users appear with Subscriber role. In general WordPress settings, it is set as Author. When I disable your plugin, I see new user with Author role, so I think that your plugin somehow sets the role for new users as Subscriber. Maybe I’m wrong, but I don’t see how to change it. Could you please help me? The plugin is good and I need it.