Other people have successfully used Ultrawide with Conan Exiles, albeit with some issues.
If you share the image that you want to upload to somewhere like Steam or Imgur, then post the link in a “broken” format (i.e. like www. google. com / something) someone will probably update the link for you so others can see it.
It’s a standard measure to minimise the reach of spam accounts. While it’s not ideal for new users, it does ensure that people have to spend a minimum time using the forum before they can upload anything.
Read a few more posts and interact with the forum for about 10 minutes and you will be able to both post and send forum messages pretty quickly.