Ok, I have been able to figure this out on my own. Apparently it is not enough ti follow the guides from
you also need to follow this: Unrealのクイックスタート | ARCore | Google Developers
Long story short, it is very important to install arcore-preview.apk as it is not installed to your device by default. You DO NOT need to build the engine from source.
P.S. Chance Ivey if you are reading this, when you make a video I would suggest double checking the information provided is enough to do something from A to Z. You really missed the most crucial part of the thing. Shame.