Using my flint behind unifi USG gateway

Hi guys

New here and looking for some help setting up my flint behind my parents USG.

We have 2 separate houses and one Internet connection 1gbit fibre.

We want to encrypt all our traffic with the built in Vpn on the flint, from our house , through their network which has a USG.

How would we setup the flint to use it's wan port into my parents network?

Thanks in advance

Matt

By just plugging it into the port of your parents network.
So: WAN Flint --> LAN USG