Sadly unlocking Redmi Note4 is not simple at all. It involved downloading a windows exe
A slight compromise would be to run the unlocking program on a virtual machine. This post has some steps on how to achieve it. https://spino.tech/blog/redmi-note-4-mtk-bootloader-unlocking-using-linux/
The first thing you’ve to do is to fill up the form on their website to download the software called Mi Unlock. Mi Unlock only works for windows.
Even if you download Mi Unlock you need to wait for at least 7 days after filling the form on their website, before you can unlock the phone.
Sometimes you won’t find the form and you can download the .exe file directly, which means yours is a trusted device, so the unlocking process may take around 3-4 days.