Using the Ajour addon manager, and one of its features is that you can supply a URL to a github and it will pull the addon down from there.

However, it has a requirement to be able to do that, that "the addon must be published as a release asset". Apparently MBB is not published as such, so Ajour cannot see it to download it as a release.

Could you mark the releases of MBB as a "release asset" please? Thanks in advance!

I can look into this. I also need to make a new project on curseforge as the person who owns this project there didn't fix their account and it's not being published properly

Got Cureforge all sorted with some excellent help from their staff. Will make a push to trigger a new package being available.