Welcome Skip! For FSX/P3D users, all of the RTMM sceneries are built on the Tongass freeware and the 3 ORBX payware regions. They are required to see the scenes as they are meant to look in each of the areas. It is important to note, however, that you can install all of the RTMM sceneries and then just add Tongass and maybe one of the Orbx regions like PFJ since it shares a border with Tongass. That would give you a large area to fly in while you stay out of the areas where you don't have the payware regions installed yet. Later, you can add the next payware region when you have funds etc.
So, the RTMM sceneries will all install but will not look right in the areas where you have not yet installed the regions.
Rod