This forum is provided by EA but is designed as Player helping Player, in this case we can not do much for you
or I should say I can not help, I have not started the new expansion and have no idea what it is about or how to do it
but I am the only one answering questions here regularly and I think it is better to give a reply that "I do not know" rather than leave it unanswered
and to provide a link to support
Contact support: Get there in game: green ... button at the bottom of the screen; info > online support
Or use the web https://help.ea.com/en/help-top-issues/?product=the-sims-freeplay
Or contact support via FB or Twitter, links are at the bottom of the page