About screenshots/inline images and editing see: For Best Results - Read the Label - good on you for using your words in the mean time 😉
About space, do the math, but first confirm the trash has been emptied.
That math includes all of these, at the same time:
- Swap space macOS needs to breath
- Space to download whatever
- Space to unpack the download
- Space to hold the unpacked download when mounted
- Space to install the unpacked download
I'd casually estimate that, with current tools, to be around 30 GB.
Additionally, space to download and install add-on components.
Off hand, unless something has changed recently, I'd normally say that at a minimum, 77 GB should be enough, not that I'd advocate keeping it that low, so as an exercise only, you should have enough at that level. Real world, all bets are off, as not being able to look over your shoulder cold shoulders further analysis.
With persisting app store admontions at 77 GB free, something in your case is atypical, I think. At the risk of blaming the victim, it might be more about housekeeping in general than it is about the tools and the store, unless of course the store has recently raised requirements vs. what it took to make it squeal in the past.
Want to live large, take the hint and get a larger drive/SSD...now. Estimate what you think you'll need in total drive capacity, then double that figure, then double it again and go shopping. Drives are not that expensive and when it comes to being a serious dev, it's just another part of doing business.
All that said, there are reports of the low space message being a bug (with the store?), so if you're happy that you have enough, check threads here for steps that might help get around it.
Good luck.