access folder from remote system

Question

need a secure connection from a remote workstation to a specific folder of the second site. Do not want other access beyond data transfer between this folder and the one workstation.

DouglasFoster · Answer

SMB is not encrypted, so you need a VPN tunnel between the two devices. 
 Since you want to restrict access to one source device, it needs to be a VPN tunnel rather than a VPN client connection. 
 Then you need a firewall rule based on source IP, destination IP, and target port. Same as any other firewall product. SMBv2 uses port 445. 
 Is there some additional complexity that you did not explain in your first post?