With URE Pro active, activating Sign-Up Sheets Pro did not create the sign-up manager role it is supposed to. Also, on the All Sheets page, there is no Add Sheet button like there is supposed to be.
When I activated Sign-Up Sheets Pro with URE Pro disabled, then the role was created, and the Add sheet button is there but as soon as I activate URE Pro, the button is gone. As long as URE Pro is active, there is no Add Sheet button for Sign-Up Sheets Pro.
There is a free version of the plugin (Sign-Up Sheets) but the pro version requires authorization so you will have to get a copy from the developer of the pro version. The developer is informed of the issue and told me they would speak with you.