I got the bootloader unlocked
To install TWRP
Download latest recovery
https://www.androidfilehost.com/?fid=673368273298930581
extract and put the recovery.img (rename if other name) on adb
Start Windows command prompt by pressing <Windows key> + X and then choosing "Command Prompt (Admin)". Once console (black box) opens, go to Minimal ADB and Fastboot folder on your PC by typing
> cd C:\ADB
> C:
(change C: and ADB to your respective drive and path you chose)
Power off your device and turn it back on Fastboot mode. In order to enter the "fastboot mode", press and hold "Power+Volume Down" buttons
Connetc phone to pc
And type
fastboot devices
fastboot flash recovery recovery.img
fastboot reboot recovery
If you want xiaomi.eu rom and your android version is 5.1 and want to upgrade to android 7 you need to flash
6/12/22 rom
https://www.androidfilehost.com/?fid=745425885120695164
then flash latest developer rom, probably the bootloader will be locked just unlock again by unlock tool.
just download rom, copy to internal memory, then turn off phone, enter in twrp and wipe cache, wipe data, install the zip of xiaomi.eu 6/12/22 then install Latest developer rom and reboot done,
after that you have to unlock bootlader and install twrp again, just follow the above steps to install recovery
the unlock tool works on xiaomi.eu roms atleast for me worked
if you have permission to unlock
http://bigota.d.miui.com/miflashunlock/MiFlashUnlock_1.1.0317.1_en.zip
Step 1.Enable developer option on phone
Step 2. Download the Mi Unlock app to PC, and sign in with your Mi Account;
Step 3. Shut down your phone manually, and hold Volume down key and Power button to enter Fastboot mode;
Step 4. Connect your phone to PC using USB cable and click "Unlock".
if you have problems unlocking the phone just follow this
http://en.miui.com/thread-202290-1-1.html