OKTA different okta domain for different requests

I'm trying to use the okta api. I was able to use the api to create an authorization server and access policy with my okta domain.

The problem started when I tried adding a rule to the policy. When I tried adding a rule with my regular okta domain which looks like this: dev-1345678. I got a 200 response but no rule was actually added to the policy. I then checked the request through the browser when adding one through the api and noticed that they're using a different okta domain. Only when I used that domain did I get a 201 request instead of 200, and the rule was actually created.

How do I know when I need to use the domain with the "admin" in the url and when not?