FloorGen Tools 3dsMax script is not the Floorgenerator plugin. The script requeres plugin to be installed (at least Free version).
The script contains additional features for Floorgenerator plugin to improve your workflow and compensate some plugin restrictions.
Add floorgenerator modifier to any object
One floorgenerator instance
Pick floorgenerator instance
Select objects with same FG modifier
Align X Y axes manually
Mirror and Flip normals
Local Rotate and keep instancing
Local Offset and keep instancing
Pick Offset points
Auto UV correction