I put a NAT router behind a Hotspot as I plug a cable on the router gets the login page. The first person to connect by cable allow everyone to connect to the internet whether by wifi or cable
please do you have a solution?
Unfortunately for you this is working correctly. All subsequent connections from the nat router use the same IP/MAC that authenticated so the hotspot thinks its all the same user.
You need to not use nat in your router.
If its a home router (WiFi with a wan port and some lan Ethernet ports) then disable DHCP on the router and use one of the lan Ethernet ports to connect to the Mikrotik not the Wan port. This will effectively make the router a WiFi bridge