Yo. Go Window->Plugins. Is substance showing up there? If not, you haven’t got the plugin installed correctly. Probably you have, and you’re just having trouble wrangling the import thing, which is understandable, it’s weird.
From memory, you need to import textures as Substance textures, which is annoying. When you go to import a texture, hit the dropdown where it probably says “all files” or something and select “substance jpg” “jpg as substance” or whatever. If you’ve imported the B2M content to your project you should have a… I forget the name of the thing, but some special Substance-related item type you can feed that texture into as the Main Input and away you go. I am hungover as heck, this might not be helpful