Hi, I'm not new to the orbiter. I would like to return to it, but unfortunately I cannot download add-ons from https://www.alteaaerospace.com/. To do this, I must have the appropriate permissions on this forum. How do I do that?
To answer your question, the permissions page shown literally says how to do that:
You are now at one approved post (the post you made above), so just making a second, non-spam post will grant your account full forum membership, including the ability to download add-ons in the 'Orbitnauts Only' category.