Issue
Are you trying to embed a canvas app in a model driven app and seeing this error - “We are having trouble displaying this app”?

We are having trouble displaying this app

Solution

There is a Canvas App Entity/Table that the user needs ‘Read’ access to. To provide this access, navigate to
Advanced Settings -> Security -> Security Roles -> -> Customizations -> Canvas App -> Provide Read Access at Organization level

Screenshots below -

After you have followed the above steps, refresh the model driven app and you should see the embedded canvas app.

Happy PowerApping!