This setting allows you to configure OneDrive silently using the primary Windows account.
If you enable this setting, OneDrive will attempt to sign in to OneDrive for Business using these credentials. OneDrive will check the space on disk before syncing, and if it is large OneDrive will prompt the user to choose their folders. The threshold for which the user is prompted can be configured using DiskSpaceCheckThresholdMB. OneDrive will attempt to sign in on every account on the machine and once successful, that account will no longer attempt silent configuration.
If you enable this setting, ADAL must be enabled or the account configuration will fail.
If you enable this setting and the user is using the legacy OneDrive for Business sync client, the new client will attempt to take over sync from the legacy client. If successful OneDrive will persist the user's sync settings from the legacy client.
If you disable this setting, OneDrive will not attempt to automatically sign in users.
Other settings which are useful with SilentAccountConfig include DiskSpaceCheckThresholdMB, and DefaultRootDir.