Partner authentication is mandatory for requesting any partner endpoints. A partner's authentication is different from the company/dispatcher authentication. This is performed by a partner API key. To call any partner API, partner API key must be included in the header of the request as a value to the custom header "PARTNER-API-KEY".
PARTNER-API-KEY: <partner api key>
curl ... -H 'PARTNER-API-KEY: <partner api key>' ...
Typically, a partner api key is a 64 characters long string.