I tried to read your original message again and noticed that you may some problem which isn’t a problem at all. I opened the project with v5.1 on Linux and it works OK. For schematic you have to accept remapping. Then the schematic is OK. The layout can also be opened without problems.
If you don’t need to actually change footprints, everything seems to be good. The PCB can be updated from the schematic, it reconnects nets but they seem to be functionally identical, DRC shows 0 problems.
Is “typon” a typo? I don’t know what it could be, I can’t find search results.
Probably the tutorial isn’t relevant for this use case, and your perceived problem is about KiCad libraries in general. For that, see the FAQ articles about library management. If you want to learn KiCad for other than just this project it’s worth getting familiar with. If you need to make modifications to the board file it’s necessary to have a correct library setup, otherwise it’s difficult to add new components.