0.18.4 installed, 'Help/Help' does not bring up qt5-assistant

[BrrrKnee]

I had installed 0.18.4 via sudo apt install freecad on Ubuntu 20.04.
looking at its documents, a link to installing documentation gave me the heads up that I needed to install qt-assistant (now qt5-assistant)

I installed qt5-assistant, also via apt install, downloaded that webpage's link to a 7z file with 2 qt files, freecad.qhc and freecad.qch.
it also mentions that to register these files, I needed to, from within FreeCAD, click menu Help, then its 1st entry Help (F1).
Neither Help/Help or F1 brought up qt5-assistant.
I thought that having to install a program to handle the help was odd; qt5-assistant should have been a dependency for the Ubuntu/deb package freecad.
Nonetheless, thinking also that installing qt after freecad, maybe a link-up failed when freecad didn't find qt. So I removed (uninstalled) freecad, then reinstalled, now with qt already there.
Same thing, Help/Help or F1 do not bring up the qt5-assistant to show help documentation.

What could be wrong here? I didn't miss any steps that I'm aware of, and I had gotten the qt files to the /usr/share/doc/freecad-doc folder; perplexed newb.

[Kunda1]

Consider updating to v0.19 at least (v0.20dev is better since we're just about to release it). And instead of distro install...opt for one of the binary-esque type installs (AppImage, Snap, PPA) it's less of a headache to get to work (less issues with 3rd party dependencies)