The problem is, you can create as many Mi accounts as you want. They can make it slightly harder by verifying your phone number, but that’s also pretty easy to circumvent.
Don't sweat it. The link for the official tool in the official xiaomi site directs to an old version that didn't work for my old phone.
I found The latest version in xdaforums, and that worked, thankfully.
The whole xiaomi experience is very unpolished. The siteS are a mess for this, the tool looks like a cooked homebrew, and their English doesn't look official.
There are unofficial unlock tools on Linux / macOS, though: https://github.com/topminipie/awesome-xiaomi-bootloader-unlo...
The problem is, you can create as many Mi accounts as you want. They can make it slightly harder by verifying your phone number, but that’s also pretty easy to circumvent.