Need Help Upgrading OS of Alcatel OneTouch Pixi 3 (3.5) to Android 5.0 Lollipop

Hi all!

I just got an alcatel onetouch pixi 3 (3.5) solely for a particular purpose, for which I need it to be on Android 5.0 for.. (it's currently on Android KitKat)
I've done an extensive search and just really struggling to understand how to do a lot of it! (granted - a lot of the information was outdated as well). So I would appreciate some help please!
So I think I've managed to root it with KingRoot. I keep seeing that I need to "unlock bootloader" - but i dont see any of those options where i could unlock OEM.
I THINK I installed TWRP via flashify - but i don't really understand what it is or if i've done it right. When I follow the steps in this video, I can't kick my phone into recovery mode even holding the power and volume up button. https://www.youtube.com/watch?v=5Kswx9frrFc

What am i doing wrong?? Would appreciate if someone could nudge me in the right direction. I'm pretty competent with tech (but I've mainly used apple stuff - so all these terms like 'bootloading' or 'flash' or 'ROM' I really have no idea….)

Thanks!