Trying to export textures with an .fbx file, but I just get an unusable file instead

So I have a model I’ve made in Blender and I want to export it to Unity/Unreal. The issue I have is that I’ve added my own textures to the model and they don’t exportl. Now I’ve read that if I use a certain method, it will export them/the UV settings so when I add them into Unity/Unreal, I just need to link the images and my textures will show up as they do in Blender. When I use the method instead of seeing my model in the programs, I get nothing. Trying to reopen the file in blender ends with an error.

This is the video I followed: https://www.youtube.com/watch?v=kEP34CbPWUo

Is there anything I’m missing? I know this is a basic issue, but I’m a little stumped. Using blender 2.83.

Which is…?