From Migration Manager Console | Tools | Agent Manager...
When try to install the Directory Synchronization Agent, its getting an error:
"An Unknown disconnect reason has occurred. (2825)"
This is due to the target computer had been configured to use Network Level Authentication for the remote desktop connection.
Change remote desktop connection setting in the target computer to use "Allow connections from computers running any version of Remote Desktop (less secure)", and perform the Agent installation again from the Migration Manager Console
Copy DSA.msi which default located at %programfiles%\Quest Software\Migration Manager\Common\BIN\DeployDistr to the target computer and run the installer manually.