Flash guide to install Ancient ROM on MI A3 based on fw11

1 - Boot your device into fastboot mode:
adb reboot bootloader   (or power off and power on again
while pressing Power + Vol Down)
2 - Flash LineageOS recovery via fastboot
fastboot flash boot <name of the file>
3 - Reboot to recovery
4 - Perform factory reset (formatting data is important)
5 - Here you have 2 choices to install rom
1) Apply update > apply from ADB
on PC open terminal and type - adb sideload <rom zip name>
2) Apply update > install from sdcard
Just copy rom to the sdcard and install it.
6 - Reboot recovery (Advanced > Reboot to recovery)
7 - Now you can install other zips if needed by using the methods
described in the 5'th line of guide.
8 - Reboot to system.

* For new Magisk versions change file extension to zip to be able to
flash it.
* This guide is based on Lineage OS recovery.
* Not recommended to use any other custom recoveries on fw11
based roms, it can cause issues for the phone.