Easy peasy I hope. First thing is confirm both end units are connected to the VPN and showing via the Road warrior GUI.
Next, make sure you can ping the end device you are after so from pc-user1 I pinged the IP address of pc-user2 in this demo @ 10.55.0.2
If you can ping, attempt to RDP to the device via it’s OpenVPN IP address. If you cannot ping the end device you may be blocked by the Windows firewall (I had to disable mine on a Win10 machine on the Guest network to confirm that was the issue). If you confirm the Windows firewall is giving you problems, you may need to create a firewall rule to allow the incoming traffic.
EDIT - seems you fixed the RDP issue before I posted.