How To Make Installed Terrain Materials Paintable

I just purchased a landscape package that includes terrain materials and have the textures and materials in my game contents. What do I do now to be able to paint the materials on my landscape?

is the ‘landscape layer’ built?
have you assigned the landscape material to the terrain?
did you press the ‘+’ button in the paint layers to create a ‘your material_LayerInfo’ (usually weighted layer)?

if you’re not sure on these things, check youtube for landscapes, you should find what you need…