Hello folks,
I had the same problem described here(I couldn't replay the topic so I opened this one):
The solution is to uninstall the Arduino IDE 2.X.X and install the older 1.X.X version, add the boards in the Preference, then uninstall the 1.X.X version and reinstall the 2.X.X version. After all that reinstalling back and forth, you should be able to find the boards in the Board Manager
Not sure about the exact issue. Version 2.2.1, on one PC I can install boards normally, and on another PC I can not install the boards. That is why I had to figure out the fix with reinstalling the old version to add the Preference link.
Please describe step-by-step "on another PC I can not install the boards": what are you doing to install an additional board and what you are getting? If possible, take a screenshot of the settings (Win-shift-S then paste here is enough).