its obligatory to have the harem route to unlock the new content with Charlotte?
Viewing post in StarMaker 1.3 Routing Questions (and future updates)
You have to be with Anna in Charlotte's yacht to get her to join the studio. It's a bit poorly telegraphed, but choosing Charlotte means you're keeping your relations with her separate from Anna, and choosing Anna is having threesomes with the two of them, and you need to choose Anna to unlock Charlotte. They really should signpost it better.