You need to register an application with Symantec Endpoint Protection Manager (SEPM) and acquire the access token and refresh token to set up your application.
Follow these steps to register your application and acquire the necessary tokens. The actual hostname may be used instead of "localhost" (accepting the security risk for the self-signed certificate):
For additional OAuth information, please review the Web Services Documentation included in the Tools folder of the product's Full Installation archive. (The archive may be extracted to disk with 7zip, WinRAR or similar.).
Run the index.html file from \Tools\WebServicesDocumentation\SEPM_WebService_SDK\ReferenceGuide in a preferred browser to view. Double-clicking will launch the html file in the default browser.