Hey, great question! This actually forced me to learn something as well.
I "believe" that the ASM - PBR Metallic Roughness template is what ultimately replaced the template I use in the video. I think this will enable you to have the closest experience to what we cover in the course!
Are you able to see what types of channels that particular template will allow you to work on? You'll want Base Colour, Normal, Height, Roughness, Metallic at the very least.
RE: Compute Tangent Space - My understanding on that is "it depends". It will depend on where you ultimately desire to display this model with your normal map on it. Different software use different processes of displaying model and texture normals, some calculating per vertex while others per pixel.
With all that said, if you intend to display this in either Blender or Unreal Engine, go ahead and enable the check box to Calculate Tangent Space. It "does" matter somewhat, but if you aren't having any rendering issues of your model and textures then I would say it is a mitigable issue at worst.
Hopefully that provided some clarity!