The idea of a bash script is that it's easier to understand and follow than say - go code.
We don't have a doc page yet that explains each part step by step. I like the idea though and filed an issue explain configuring a simple overlay · Issue #991 · openziti/ziti-doc · GitHub We have this, but it's not quite detailed enough Quickstart Walkthrough | OpenZiti
I've gone through it numerous times here on the forums and numerous times on YouTube. Here's one that I did last year for a discourse user (referenced on this post):
It comes with a very short set of commands I added to a gist that is a very minimal setup: openziti-compose/from-scratch.sh at main · dovholuknf/openziti-compose · GitHub
You can also get down and dirty with openssl and create your PKI manually if you wish. A forum member contributed a github repo a few months back: GitHub - nenkoru/openziti_manual_pki: Bootstrap PKI for OpenZiti manually
And I went through that whole thing on Ziti TV too here:
Hope those help.