Paul,
Create a Package called package as ADMIN and then execute the following script:
-- Create REPO_READ_ROLE Role
CREATE ROLE REPO_READ_ROLE;
-- Assign GRANTED ROLES to ROLE
GRANT EXECUTE on REPOSITORY_REST to REPO_READ_ROLE;
-- Assign SQL/Object Privileges
GRANT SELECT ON SCHEMA _SYS_BI to REPO_READ_ROLE;
GRANT SELECT ON SCHEMA _SYS_BIC to REPO_READ_ROLE;
GRANT SELECT ON SCHEMA _SYS_REPO to REPO_READ_ROLE;
-- Assign Package Privileges
GRANT REPO.READ on "package" to REPO_READ_ROLE;
-- Create REPO_READ_ONLY Users
CREATE USER REPO01 PASSWORD Hana1234;
--Grant role to REPO_READ_ONLY Users
GRANT REPO_READ_ROLE TO REPO01;