You can attach your unfolds to your post with the "Attach files" option on any post to share them, with no post number restrictions.
To submit them for submission to The Armory in the site, use the form at the top of the page, "Submit Fikes to the 405th Armory. "
This also has no post number restrictions.
I do not know who told you that you were required to have 50 posts to submit files, but the only thing that has a post restriction is joining a Regiment and subsequently submitting a completed costume for the Deployment process.