Jira service desk API works for agents but not for customers

[PaulaA]

Hi there, 

I'm trying to figure out how could I help some customers to use basic API calls. 

When I run this one on the browser:  <jira-home>/rest/api/2/search?jql=resolution+is+empty

I get a bunch of results with al my assigned issues. 

When I do the same being a customer without the internal access, then I get redirected to the customer portal as if I'm logging in.

It is the same if I do the call saying I'm the reporter ( so a real case for a customer) but I get always back to the customer portal 

How can I adapt the API call so the customers can use it to get all open issues in their projects.