I just looked into this with an agent in Dubai and was told the following, as I was planning to follow the same setup myself.
If you're trading your own funds and not offering services to others, you generally don’t need a license in the UAE, especially if the trading is done via a foreign brokerage (like in the US).
But if you're actively trading as a full time business activity, it might be smart to look at a freezone license just to stay compliant. Something like a consultancy or general trading license (even if not used for clients) can cover you.
Check out DMCC, IFZA, or Meydan Free Zone, they’re popular and flexible with online activity.