https://www.snopes.com/fact-check/trump-campaign-actors-announcement/]
The report notes that while the Trump campaign denied knowing about hired actors, it did pay $12,000 to a contractor (Gotham) four months after the event took place. The report also notes that Gotham hired Extra Mile Casting as a subcontractor to provide administrative support at Trumps announcement.
Both the campaign and Gotham gave vague descriptions of the services provided by Extra Mile, but the FEC report notes those services included providing at least some of the rally attendees:
It is not uncommon for campaigns to hire companies or Casting agencies like Extra Mile to generate a crowd at an event. In this matter, the available information indicates that the Committee retained Gotham as an event consultant, and Gotham, in turn, subcontracted with Extra Mile to provide extra administrative support at Trumps announcement, including the provision of at least some of the rally crowd.
The FEC, citing the modest amount of money at play, declined to prosecute the Trump campaign on accusations of campaign-finance violations.
The practice of astroturfing or hiring actors to give a political candidate or movement the appearance of having popular support isnt unheard of. As the Atlantic reported in 2015, These days, if a candidate or protest organizer is short on numbers, he or she can simply pick up the phone and call a company like Crowds on Demand, a Los Angeles-based company that provides rental crowds for campaign rallies and protests.
Of course, red don now has many authentic idiots supporting him.