Default logon credentials used to access the SharePoint server can be configured in this section. If you configure a Username and Password here, it will be used by default if you leave the Username and Password fields blank in the properties of SharePoint web parts.
If you enable the Use Windows Authentication option, the current user's windows domain credentials will be used to access the SharePoint server.
The address of the SharePoint server itself needs to be specified in the properties of SharePoint web parts.
The settings configured here are automatically used for authentication by the GetSharePointFile.aspx page and since the URL to access the page can be entered manually, it is highly recommended to enter the credentials of a user that is authorized to access only the files you want to display on your website.
More resources can be found at Developer's Guide -> Modules -> SharePoint integration.