Why can't I paint my landscape?

I am using the landscape material from this video: https://www.youtube.com/watch?v=5ju7wyvZGBI&t=2639s

Whenever I imported the files into my own creation, it didn’t assign my B layer when there was a slope. At that point, I could paint. I painted on the AutoMaterial on my entire landscape because I saw that it made the slope the B material. Now, whenever I try to paint any material, it doesn’t work. I believe this is where it went wrong, but I’m not entirely sure.
Now, whenever I paint with an entirely different texture, it just changes the color, but not the texture. I am fairly new to Unreal Engine. Thank you in advance!