API calls on core DocTypes in ErpNext Demo

I have been trying to make API calls to core doctypes using postman but it doesn’t seem to work on the demo trial version on erpnext. I had done it before on the same doctypes when I had hosted it myself before. Now that my server is down, I’m just learning on the trial version. So I just wanted to know if it is the problem with the trial version or not? Because my authentication both using token and the basic authentication is being ignored. The guest user is being used for authentication.