So it will open each sub folder in the "Drums" Path and in the Batch Converter any MGU in those folders will be rendered to midi and it will just render the Melody track that contains the RealDrumCharts without generating the song up.

Same as doing it manually: Open a RealDrums MGU > File > Save Special > Save Song As MIDI File > Batch Mode > OK
so you should just get a .MID with just the drum midi and same name as the RealDrum .wav or .wma
just make sure the Audio track is not soloed.
If you choose the Piano roll view then select the Melody track you should see the Drum midi. You can Drag to MID and export but this will take too long as you need to rename them to the drum .wma name.

So basically the script makes a list of the sub directories in Drums folder then as it loops through the folders it pastes each path in the the Batch dialog then clicks Ok then Ok for notice dialog.

I did the whole Audiophile Drums folder and I got about 1226 drum midi.

Yes , AutoHotkey is easy to learn and can do so many things that users want Biab to do without waiting years for it to come to Biab. There is so much help and examples to do just about anything in the AutoHotkey forum, way more help than you would get ii the Biab forum.