Unable to "Start Alignment"

[Hileotech]

Hi!
I just saw Obsidian plug-in in a Twitter thread and wanted to give it a try.
I correctly downloaded/extracted and copied the plugin in .obsidian/my_vault_name/plugin, and I can see Dual settings in my Obsidian option panel.
I downloaded/installed Python as per instructions.
I created and copied the snapshot of my vault (a not-so-big test vault).
But as I try to "Start Alignment" I can't open the webpage linked to the button. Google says I don't have the permissions...

Running macOS 11.5.1 on a MacBook Air 2020 (not M1).
I tried with Brave browser, Google Chrome and Safari, all logged in with my Gmail account: no way. I even tried with a Chrome private session: same result.

What am I doing wrong?
Thanks!!!