Can't install Sims Medieval Pirates and Nobles

Hi all 🙂

I've been playing the Sims Medieval on my Mac for a while now and recently bought the Sims Medieval: Pirates and Nobles. When I try to install (through Origin), the installation is prevented at the stage of choosing a location, with the error message "To install the Sims Medieval Pirates and Nobles you must already have the Sims Medieval installed. Select a volume where the Sims Medieval .app is already installed." Only problem is, I am selecting the volume where TSM is installed... [My name] -> Applications. 

Does anyone have any suggestions>