You have to follow the recommendations of your ortho doc and PT. You aren’t going to be able to put pressure through that talus until they say it is ok. After that, you need to work on ankle mobility drills and foot drills to tolerance to start working back into regaining dorsiflexion. While it is in the boot, you will likely be able to work on the soft tissues of the calf and do some smashing with a roller or ball to keep the muscles and soft tissues supple as the avulsion heals.