What says the error message is that you cannot *post* (create) a new thread, but the "asset release" forum should be freely readable. And you can of course reply to any of the existing threads unless it is locked (as is the tag rule one)
Indeed, if you want to post a thread in this forum (and it should be to upload an asset and respect the posting rules), you must first post in the "asset request" forum and ask a moderator to move the post to the asset release forum. See the message https://f95zone.to/threads/asset-uploading-rules-instructions-2020-06-01.23506/