Hey Lesouf,
My name is Todd Manus, I don't have a Mac, but I'll see if I can help. With Linux and Windows 11, you can simple copy of a JSON file over from where Renderman got installed, to a folder called packages that is usually in your "houdini21.0" home folder
See the packages installation section here:
https://rmanwiki-27.pixar.com/space/RFH27/544640398/Installation+of+RenderMan+for+Houdini [
rmanwiki-27.pixar.com]
If you have question, I can try and help. You can reach me on Pixar's Renderman Discord server.
BTW, I have never seen the Renderman plugin in the Labs/Packages section ever, so I don't think you have to worry to much about the fact that it doesn't show up there.