That sounds like itch.io's spam filter rather than anything you did wrong. Posts from newer accounts often get held with an "Awaiting moderator approval" message, and they stay hidden until someone approves them. If it's a comment on a game's page, the developer of that game can usually approve it, so it may still show up later. If it keeps happening everywhere, contacting support at /support and asking them to review your account is the usual fix. This thread showing up is a good sign, since it means you can post here in the main community. Welcome to itch, it gets less confusing after the first week.