Accessing Secure Score as a Security Administrator

Try any of the custom admin https://support.office.com/en-ie/article/about-office-365-admin-roles-da585eea-f576-4f55-a1e0-87090b6aaa9d, for example, I tested a service admin account and that permitted access to Secure Score:

"Anyone who has admin permissions (global admin or a custom admin role) for an Office 365 Business Premium or Enterprise subscription can access the Secure Score at https://securescore.office.com/. Users who aren’t assigned an admin role won't be able to access Secure Score."