Explanation
Note: PAT Supported only on Azure Pipelinesand TFS 2017 and newer. After you choose PAT, paste the PAT token you created into the command prompt window. Use a personal access token (PAT) if your Azure DevOps Server or TFS instance and the agent machine are not in a trusted domain. PAT authentication is handled by your Azure DevOps Server or TFS instance instead of the domain controller.
Reference:
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/v2-linux
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/v2-linux?view=azure-devops