[US] are unregistered paid copy trading platforms legal?

The experienced trader would provide real time options and forex trade alerts and explanations of why those trades were made. The customers would pay a monthly fee for those alerts and provide their TD Ameritrade or Tradier platforms and copy the trades directly into their account via auth confirmation setup on this copy trading app platform. The monthly fee is only for the upkeep of running this copy trading that the trader built and setup, not directly as compensation.