Some engine past versions are not available

If you’re capable you can access specific versions from Github in the Tags sections and build it. But I agree with Clockwork, you’re better off with the latest version of a release.

The past versions in the epic games launcher are not complete. Eg, 4.23 is completely missing. In my case I hope to install 4.24.0, and it’s not in there either. How do I get access to those versions?

I don’t think you’re going to find 4.24.0, because 4.24.3 is the fixed version of that. Why would they leave a buggy version up?