I see, or maybe she hasn't been added as a user, since this app is in a EVERYONE stream, BTW what is the connection between mashup and published app since as far as I know mashups are not belong to streams only the apps.
The process are the following, in a case I developed the app in Desktop env.:
- app has to be imported to the server.
- mashup has to be imported to the server.
- app has to be published on of the streams, where you can manage which user can see it.
- mashup url has to be send to the user.
BTW Rob I am a big fan of your blogs comments
Best wishes from Hungary.