Hi there
These steps worked for me in Zorin pro 17 (today Oct 5, 2025).
Some other sites recommend steps that are out of date, but this one is clear and up-to-date.
I was taken in by the Zorin marketing that implies there is a windows-like desktop available 'out-of-the-box', which many others also fell for, but with the above you can get it close. There are no rounded corners on the file manager and terminal.
If you upgrade to Zorin 18 this extension will no longer work. Before upgrading (when you use the upgrader tool) you should disable all gnome extensions because they can cause problems and the extensions are only made for special gnome versions.
You can use the following one if you need rounded corners in Zorin 18.