Another way to say what I think Kent is saying is that it doesn't matter where you run the update file FROM. As has been said, it also doesn't matter where you download and save the update file.

I keep my downloaded updates (the last few, like Jim said) on a completely different drive from my BIAB installation (Drive H, in my system)

When I run the update (from drive H, but it could be from anywhere), the setup file only needs to know three things: the drive letter and path to the main BIAB installation, the drive letter and path to the RealDrums folder, and the drive letter and path to the RealTracks folder. Please check that you did this correctly. In my case, since I have the RealTracks and RealDrums on yet another different drive, I put them in these folders:

G:/BB/RealTracks
G:/BB/Drums

Note that there is nothing in G:/BB except these two folders.

My main BIAB program is here:
F:/BB

BIAB 2024 Win Audiophile. Software: Studio One 6.5 Pro, Swam horns, Acoustica-7, Notion 6; Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus Studio 192, Presonus Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors