TonyRomanelli Add --ignore-platform-reqs at the end of your command and it should work fine.
Wow, thanks a lot ! It works like a charm now ?
Well, if I could abuse a little bit, could you please give an exact command to install an extension ?
It always show me a stability problem when I try php composer.phar require ext/name-of-extension ./flarum-folder stability=beta
Thank you !