How I Installed GoodLock Features in Samsung A51?

Hello,
My name is Robert Pattorn and I belonged to USA. Recently i buy Samsung Galaxy A51 2020 from Samsung Official store. This Mobile performance is very Good but my question is:
How I Installed GoodLock Features in Samsung A51?
I am a designer and Painter which reason i want to make a good looking user interface. Recently I watched this video which url is https://www.(2021) Install Official Good Lock & Addons on Any Samsung from Any Country - YouTube.
I watched completely but I can’t understand why my mobile not supported this Features.
So, I am very glad if you can help me.
Thanks Samsung Team!