UNIFI security gateway controller behind Mikrotik CRS-109

RouterOS Beginner Basics
1

There is a situation given, sorry for my english. UNIFI Security gateway is as source of internet to Mikrotik CRS-109.
UNIFI SG : 192.168.168.1 Mikrotik router 192.168.240.240 (this address is mandatory).
I would like to connect UNIFI controller HW or controller SW in PC with UNIFI SG… it is some setting in Firewall for sure but cannot firure it out.

2

Unifi USG must be on the same L2 infrastructure as controller (PC with controller/cloud key)