maybe, I think 200 status code is for KTUCloud.
http://developer.ucloudbiz.olleh.com/export/sites/default/support/pds/download/KTucloudSS_API_V1.220130128_1.7.4.pdf
but it is written in Korean.

page 5. 사용자 인증(User Authentication) Section
page 6. Response Body <- it returns "body" 
page 6. HTTP Status Code <-- 인증 완료(Authentication Complete) -> 200, 인증 실패(Authentication Error) 401

so. it returns response body and it's status code is 200.