First time installation (clean flash):

    On your computer open Command Prompt or Terminal and go to ADB folder location
    Reboot phone to fastboot with adb reboot bootloader
    Flash lineage Recovery with command:

fastboot flash vendor_boot vendor_boot.img

    fastboot will flash recovery to active slot
    With volume buttons, go to Recovery Mode
    In lineage Recovery, go to Apply update - Apply from ADB
    After that execute this command:

adb sideload zip_name.zip (where zip_name is mistOS zip for your device)

    After ROM installation finished, recovery will ask you to switch to the opposite slot to flash ksu and/or Magisk. Select yes.
    After reboot to recovery, adb sideload ksu and/or Magisk.
    Reboot to recovery
    After reboot - Factory reset.
    Reboot and enjoy

Dirty flash via recovery:

    On your computer open Command Prompt or Terminal and go to ADB folder location
    Reboot into Recovery using adb reboot recovery
    In lineage Recovery, go to Apply update - Apply from ADB
    After that execute this command:

adb sideload zip_name.zip (where zip_name is mistOS zip for your device)

After ROM installation finished, recovery will ask you to switch to the opposite slot to flash ksu and/or Magisk. Select yes.
After reboot to recovery, adb sideload ksu and/or Magisk.
Reboot and enjoy