I never understood why I should use composer as an end-"user" either. It might have advantages to use it for development but I had never experienced any advantage in trying to maintain a site (together with all plugins!) as opposed to make use of the "traditional" way of using zip files (regardless where to fetch them from). My "version control" is the version of Elgg / the plugin the zip is supposed to contain and any differences in files can be figured out using some diff tool.

The elgg-cli commands have NEVER worked for me either! And I don't understand under which conditions they are supposed to work. I would have to execute the commands as root to get them working at all and I can't advice anyone to do that. Security aside, any files and folders created by root can't very likely not be read by the webserver just to name one other problem.

If you have a test server you might want to give composer / elgg-cli another try. You could try to get accustomed to it and then make use on your production server. Otherwise, the old fashioned way of using zip files and the browser-based installation still works (and works perfectly fine if you ask me).

As for the Elgg documentation of making use of composer I would also say that it's not really helpful. And searching the Internet (or making use of the composer docs) is not much better either because I see totally different target groups in the usual users of composer and Elgg users (admins). Just because you want to use Elgg does not mean that you are necessarily a coder. But maybe a coder does not understand that non-coders might have some trouble understanding the composer docs...

Still struggling through the same thing, but i am not asking anymore questions. I will eventually give up on it anyway, and that will be the end of it.