Connect to LAN through mikrotik connected to VPN

Hello everyone, I am trying to access one device behind mikrotik which is connected to VPN. The path should look like this.

my PC(public IP, 172.20.0.5) -> VPN server -> Mikrotik(172.20.0.4, 192.168.1.15)-> device(192.168.1.90)

I can connect to mikrotik (172.20.0.4), but I would like to somehow connect to the device behind it, port 80 would be enough for now, but I would like to know how to enter the LAN in future. I have tried forwarding the ports with setting

Dst. Address 172.20.0.4
Protocol	6 (tcp)
Dst. Port	8080
Action	dst-nat	
To Addresses	192.168.1.90
To Ports	80

When I telnet the address 172.20.0.4:8080, nothing happens, even though I opened the port in firewall.

Next I have tried static routing in my windows machine to access 192.168.1.90 though 172.20.0.4, but still no luck for me.

Can anyone please tell me how can I connect to device ?

Is the VPN server a seperate device from Mikrotik? If so, you will have to tell the VPN server how to get to 192.168.1.x subnet