OpenWrt router behind a public proxy

Yo, so basically I currently use my computer on a public Wi-Fi from my residence. I bought a router and just installed OpenWrt, what configuration do I need to make so that my home network can access the internet via the proxy router? Is it a wifi bridge ? Do I need to configure some kind of NAT on my router ? I don't have any access to the proxy router since it's public and I don't own it.
ps: my router is a xiaomi ax3000t


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