The manager is the FMC's agent so that means she is empowered to act (make decisions) for her. Its never made clear what the FMC business relationship is with the talent agency but its probably some sort of contract and that obligates her to follow their direction to some degree. Its not like not the manager is not going to consult with the FMC, as we saw later, before committing anything. But the manager is also working for the agency who has their own interests in getting a return on their own investment. There is going to be a dynamic going on where the actress may need to listen to the manager as a representative of that agency.
What this episode shows us is that the manager sees the actress as more than an assignment or product of the talent agency but as a friend when she did not immediately accept the suggestion made that they go along with the gossip paper's story.