ZeroTier on Unifi USG Pro

Hello

Trying to install Zerotier on an Unifi USG Pro

Read the KB here :

Ubiquiti | ZeroTier Documentation

And it says to output the .deb file in /config/data/firstboot/install-packages/zerotier-one.deb so it could be reinstalled automatically after firmware upgrade.

Problem is that /config/data does not exist on my USG Pro.
Maybe the KB is an old one?