getting error in project users api

getting error in project users api

Hello, I'm getting a "Given URL is wrong" error when trying to use the Zoho Projects V3 API endpoint for adding users to a project. The URL I'm using is https://projectsapi.zoho.com/api/v3/portal/{portalid}/projects/{projectid}/projectusers/ and it's returning an error with status code 400, title "URL_RULE_NOT_CONFIGURED", and the message "Given URL is wrong". I can access other project endpoints successfully, so authentication is working fine. Could someone please confirm if this is the correct V3 API endpoint for adding users to a project, or let me know what the correct endpoint should be? Thanks for any help!