If you enter the source name manually, you must type the exact name of the User, Computer, Group, or UNC Path referenced in the source GPO (for example, TestDomain\PolicyAdmins or \\server1\publicshare). The type of the source name must match the source type specified in the migration table.
Security principals can be specified using any of the following formats:
UPN: For example, someone@contoso.com.
SAM: For example, contoso\someone.
DNS: For example, contoso.com\someone.
Free text: For example, someone. You must specify the type as Free Text or SID.
SID: For example, S-1-11-111111111-111111111-1111111111-1112. You must specify the type as Free Text or SID.
Click Browse to find a user, computer, or group.
Point to Set Destination, and then click the appropriate selection. You cannot use the No Destination option for UNC paths.