Administrator

1. Can add shipment.
2. Can update shipment.
3. Can delete shipment.
4. Can assign employee.
5. Can assign agent.
6. Can assign client.
7. Can assign branch manager (if Branch Manager Add-on is activated).
8. Can assign driver (if Proof of Delivery Add-on is activated).

Employee

1. Can add shipment.
2. Can update shipment.
3. Can delete shipment.
4. Can assign agent.
5. Can assign client.
6. Can assign branch manager (if Branch Manager Add-on is activated).
7. Can assign driver (if Proof of Delivery Add-on is activated).

Agent

1. Can add shipment.
2. Can update shipment.
3. Can delete shipment.
4. Can assign driver (if Proof of Delivery Add-on is activated).

Client

1. Can track shipment through My Account page.

Branch Manager (requires Branch Manager Add-on)

1. Can update shipment.
2. Can assign agent.
3. Can assign client.
4. Can assign branch manager (if Branch Manager Add-on is activated).
5. Can assign driver (if Proof of Delivery Add-on is activated).

Driver (requires Proof of Delivery Add-on)

1. Can update shipment.

How to restrict users from accessing your wp-admin.

add_action( 'init', 'wpcargo_block_users_backend' );
function wpcargo_block_users_backend() {
    if ( is_admin() && ! current_user_can( 'administrator' ) && ! wp_doing_ajax() ) {
        wp_redirect( home_url( "my-account" ) );
        exit;
    }
}