Non Pro free users of the Trailforks app get 1 free area. This free is set automatically for you based on your current location. But you are allowed to change this ONCE to anywhere you wish.
You can either click the "Edit Free Area" text in the bottom right of the free area green box on the map. Or pan the map somewhere outside your free area and zoom into the map. Ad the map turns grey there will be an "Unlock Area" yellow button at the top of the map. If this is the first time clicking this, you will be presented an option to either Subscribe to Pro, or set your free area.