Using access to the server as a guest user (if enabled) include guestAuth before the /app/rest part, e.g. http://<TeamCity Server host>:<port>/guestAuth/app/rest/builds.
There is a way to access without using a username & password. Can you enable this feature?
From https://www.jetbrains.com/help/teamcity/rest/teamcity-rest-api-documentation.html#REST+Authentication
Using access to the server as a guest user (if enabled) include guestAuth before the /app/rest part, e.g. http://<TeamCity Server host>:<port>/guestAuth/app/rest/builds.
There is a way to access without using a username & password. Can you enable this feature?