Does TWRP Need Unloked Bootloader?

I have D855TR installed 20n stock firmware. I want to flash custom rom(Not AOSP or CM! I will flash Lollipop Stock Based ones, NOT MM! )
My question is I need to unlock bootloader to flash twrp? Can I use Flashfire or Flashify?

from xda-developers http://ift.tt/1YYZG1K
via IFTTT