Another thought:
After you install in the '\bb_2020\' folder and set the Preferences for the Drums and RealTracks locations to point to the 2021 folders, you can delete the duplicate set to save space. These would be:

\bb_2020\RealTracks\ and \bb_2020\Drums\


BIAB & RB2026 Win.(Audiophile), Windows 10 Pro & Windows 11, Cakewalk Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Session Keys Grand S & Electric R, Kontakt, Focusrite 18i20, KetronSD2, NS40M, Pioneer Active Monitors.