Port forward the relevant traffic on the NAT device in front of the RouterOS router.
Or use VPNs, if you can.
It’s configured on the NAT device in front of RouterOS. If you post information on what that is maybe someone can help you, but really that’s outside the scope of this forum as it has nothing to do with RouterOS as such.
Then you can’t access the router behind it from the Internet. Even for VPN solutions you’d need to terminate the VPN tunnel somewhere behind the NAT device, which would require ports and protocols to be forwarded.