I suspect the “Notes” layer, in the absence of a plugin like “Buli Notes” for Krita 5.x, is a layer meant to house a few notes, it may not be elegant, but the function is what matters. You could call it a workaround - anyway that’s only what I guess, I’m curious about @RamonM’s answer.
Regarding your question, are all the layers are needed for it to work, how about disabling them one by one to see what happens then?
Make a copy of the template and just play around with it, then you can even safely delete the layers to see what happens then.
Or, and this is the most convenient and safest way to use templates in the long run, create a permanent Krita template of each of the three *.KRA files contained in the ZIP archive via “File”, “Create Template From Image…”, and you will have these three templates permanently available in Krita from now on via the key combination Ctrl + N, and you won’t have to access and load them via the file manager. Templates created this way are stored in the resources’ folder, similar to presets or bundles. You can name them as you like, assign icons for better recognition, sort 'em into groups, or create them own groups.
This is what the templates look like at my site