Teams membership API returns 401

[Hyunjun _Jun_ Jyun]

Hi team,

I am experiencing an authentication issue while working with the JIRA API. Following the documentation provided in this link, I have been attempting to make API requests, but I consistently receive a 401 Unauthorized error.

I have tried various approaches and configurations, but all attempts result in the same 401 error response. This is particularly puzzling as I am an admin for some of our organization's sites, yet I am still unable to authenticate successfully.
(I've tried 

POST /gateway/api/public/teams/v1/org/ORG_ID/teams/TEAM_ID/members and 

POST public/teams/v1/org/ORG_ID/teams/TEAM_ID/members and none of them worked while getting a team information did work)

Could you please help me understand what might be causing this authentication failure? I would greatly appreciate any guidance on resolving this issue. Please let me know if you need any information.

Thank you for your time and assistance.