Users must be assigned to the M3_H5_Client_Enterprise/Mashup-Administrator role to use web mashups and access the Mashup Administration Client. See Mashup Server (Runtime of Mashups).
Take note of the difference between these users:
app-admin – This role grants access to all configuration and operational tasks for a particular application.
app-user – This role grants access to application defined operations.
Mashup-Administrator – This is an administration role for managing mashup applications.
Mashup-User – This role grants access to running mashup applications.