We solved it via the support mail account, but as a reference for anyone going through the same issue:
In macOS, all the stuff you see in the Applications directory IS a directory, which you can open by choosing "Show Package Contents" from the contextual menu (the one you get with Right Click or Cmd+Click).
So, when you open Applications/ERA-Mac, the ERA icon you see is what macOS calls ERA.app
You should right-click/cmd+click on the ERA icon, choose "Show Package Contents", then navigate to Contents, Resources, RMFRP.
In there you will find the files for Adventures, Characters and Configuration.