Thread:Project:Support desk/Installing extension on 1.19.1/reply

Quite often the supported version list of an extension is out of date. Generally (not always) an extension marked 1.17 will work with 1.19. More rarely an extension marked 1.19 will work with 1.17, but that's much more rare. Often extensions have old versions available for older versions of MediaWiki. So basically, try it and see. If things don't work, just remove the extension.

I don't know why you couldn't download AccessControl. You might have better luck downloading directly from the repo.