Well, that was an easy reply. Is there something about their architecture that stops the app working? It would be nice if the Playstore App could work at some point in the future as they are becoming a popular replacement for Android tablets.
I got my Chromebook to work with the core on my Win10/64 PC by going into the Windows Firewall settings and allowing the item that controls communication with another machine but only on a local network. Then I typed in the IP address of the core machine directly in Roon Remote on the Chromebook. Connects every time now. Try it.