Fixing up this space.

My sister and I recently came into this space https://imgur.com/a/r14Oyhu , we want to use it to practice pole fitness. We pretty much have free rein to do what we want improvement wise. The garage door is coming off the ceiling. Our main concern is humidity in the warmer months and being cold in the winter. We want to wait a bit before pouring a large amount of money into it, until we're sure we'll stay past a year.

What would you start with? Open to all suggestions. Thanks