Believe me, every day at least one user asks the same question.
Why don't you and others do not read when they ask and get answered.
It's pretty selfish not to waste time reading what others post, but then to expect the others have to spend time on your post - to read and answer (always the same thing, again and again)
And what for the first page, OP posts with instructions are written - are those instructions not worth to read or what?
There are two types of ROM. Fastboot and recovery. From the name of the Xiaomi.eu ROM you downloaded, you can read is it Fastboot or Recovery type - or you can read that directly from the table in the post #1. Find your device in that table and from the last column read do you have Fastboot or Recovery ROM type
And things change - and therefore you have to spend just a minute or two each week when you update, to see if for your device the ROM type switched from Fastboot to Recovery - they do, once TWRP for your device supporting A12 becomes available
And then, follow the instructions describing how Recovery ROM type has to be installed
As simple as that - read instructions and follow the discussion to be up to date