The plugin work in this order:
1. Select 1 or more rooms. If are more only first will be computed.
2. Menu->Tool->Generate roof...
Recommendation 1: try on a test file, eventually with file provided on this page.
Recommendation 2: install AutoDimensioning plugin, read instructions , and, if You have some walls, will generate roof projection for that walls.

NOTE 1: If roof are not generated correctly, try to modify a little bit the foot print to avoid some edges to be collinear.
NOTE 2: Even so will not work all the time!

PS: I've try to reproduce Your building and with v.1.0 work!
Verify in Help->About Your installed version.
The result are not total correct (some faces) but it work.

The size of the building I am making is around 268ft long in the left to right direction, if that helps any... I believe I have the autodimensioning plugin, and will try that, but as for you getting it to work, depending on what faces work, it might work in my case, as the roof is just to make the building feel complete in any pictures or videos made.. also remember, that my playground will be the big thing that will be the focus, as the building is already built, but I am doing a design for my church, who's kids are supporting another church in building a playground, so I thought I'd take the rudimentary mspaint looking drawing with post-it notes and added pictures, and try making a quick 3d design...