API Keys are authenticated on a per-user basis. To access a team, you'll need to obtain the owner's API key.
Obtaining an API Key
You can obtain an API Key via https://app.interseller.io/integrations/api
Authenticating Requests
Once you've obtained an API key, you must pass it to every request as a header via X-API-Key
Authentication Errors
If you see 401 Unauthorized, your API key is missing or something else went wrong. In that case, you should check the body of the request for an error code.
If you see 403 Forbidden, your API key was accepted but the resource you are trying to access is not available to you.