It gives you a notification to Install SWS Extensions for Reaper from https://www.sws-extension.org/

I updated the script in the previous message, you can swap the new ones with the old by just replacing them in the script folder.
You don't need to generate up Stems in Biab just the normal drum track then freeze the SGU and open in Reaper,
then run Script: Create stems from selected realdrums stereo track.lua

If you have generated up stems and froze the Mix track it will automatically import all drum stem tracks and you won't have to run Script: Create stems from selected realdrums stereo track.lua

Is it importing any tracks, there is no pic of Reaper tracks ?

You don't need the PG VST to load the SGU track/s in.