BFD3 isn’t integrated with the inMusic Software Center yet, afaik. The next BFD3 build is supposed to ditch the current License Manager and presumably use the inMusic Software Center.
In the LM, the default download location is set to, user/Documents, but that is just for the installers. When you run the installers, you can choose a specific location to install the actual expansion content.
In the LM, you can choose a different “Downloads” location by going into the LM Preferences.
I’ve had that issue, where the LM is not showing expansions as installed, even though they worked fine in BFD3. The easiest (yet tedious) thing to do is just install them again. I would just leave it, as it’s working fine. You can try editing one of the preferences files, but that only worked for me one time.