Yes, it needs time without weight on it to begin healing which is something they may not have been clear about.
This is probably a reason why it has not healed yet. It needs some time without stress so it can repair.
The time in the cast will keep things from moving so it can heal.
There may not be anything else going on. Wasn’t sure where it was 2 months without being healed, but the above was an impacting factor.

You can workout using your healthy limbs for the time being.
Pick an aspect of upper body strength to work on. Floor press, seated press etc.
You can do skill work learn a new skill, improve a skill, or address a weakness in performance.
Gymnastics skills such as ring dips, L sit/L hold, skin the cat are some options.
If you have access to a hand bike as an option for a cardio work out or swimming with 1 foot push offs.