What permissions are required for complex cross-schema materialized view in Oracle?
The issue appears to be the "ON COMMIT" portion of your DDL. From the documentation:

"To create a refresh-on-commit materialized view (REFRESH ON COMMIT clause), in addition to the preceding privileges, you must have the ON COMMIT REFRESH object privilege on any master tables that you do not own or you must have the ON COMMIT REFRESH system privilege."

So either go with "ON DEMAND" or grant the additional privilege for each source table.