Quenti I'm sorry that this is causing you some frustration. We're not trying to make this process difficult, simply consistent for our community.
In Flarum, our extensions are installed and removed through Composer. This is an essential part, because it simplifies what would otherwise be a complex mess of file editing and folder shuffling. We don't want our users to go through that process, and Composer makes it easy.
You can read in our documentation how this procedure works. We don't require the use of sites like Github and Packagist (and as clarkwinkelmann mentioned these are not the only options, simply the most commonly used) to burden our extension developers, most of them find it a convenient method for hosting and distribution. Using them also relieves Flarum of the need to provide hosting and serving files to our users, which would greatly increase our costs, and only duplicate what's already available in Github and Packagist.
Since you do have a Github account for your repository, using Packagist should be a simple matter since you can log in with your Github account. The instructions I gave, as well as instructions on Packagist's website, should walk you through the process of getting it working. When the release is tagged and picked up by Packagist, which usually happens within an hour, your extension should be able to be installed via composer require Mejans/lang-occitan.
Please know that we greatly appreciate the efforts of our extension developers, and especially those who translate the languages. We also appreciate the variety of different users who come to Flarum, and we aim to provide them with a consistent method for obtaining extensions. This is how we treat our community, with consistency, so I hope you understand the reasons for the requests here.
