i took some information from the official docs of Zen Browser: here

You wanna change computer, or installing another OS, but Zen Browser doesn't save all the Pinned Tabs and Essentials that will surely be really tedious to setup all over again??

Worries not, I've got you covered!

1. locate your profile folder

go to about:profiles (type it into your address bar)
find your profile and look for the Root Directory