If you want to build an integration that calls the LiveChat APIs, you'll need to implement an authorization flow and configure the App authorization building block.
It is OAuth 2.1 that is used to securely access the data of the HelpDesk users.
HelpDesk API shares an authentication and authorization system with LiveChat. If you want to build an integration within HelpDesk, you'll need to configure the App authorization building block and authenticate or authorize within HelpDesk.
To read more about authenticating or authorizing within HelpDesk, take a look at: