All Zoho Billing Endopints return 404

All Zoho Billing Endopints return 404

I am on a trial and trying to test the API (via the Postman collection) and ensure it will work for our use case. I am able to get an OAuth token, but every endpoint from the Billing docs returns 404: invalid URL. I confirmed I am using the base URL from the documentation but still no dice. Any suggestions?

Docs:https://www.zoho.com/billing/api/v1/introduction/#overview
Base URL: https://www.zohoapis.com/billing/