@Anonymous RBAC roles are at the Azure subscription level where you define the permission to the user for different operations over your Azure subscription. Whereas APIM APIs are created at the APIM level and to Consume the published APIs you need to pass the valid subscription key in the HTTP requests when calling to those APIs. Without a valid subscription key, the calls will be rejected immediately by the API Management gateway and the request will not be forwarded to the back-end services. You can refer to APIM subscription document for more details.
In nutshell, you cannot use RBAC permission to authenticate the APIM APIs.