Yes, the video series should have an update to explain individual user accounts should be selected when creating the project, because VS 2019 defaults to no auth, which prevents scaffolding out Entity Framework and Identity libraries.
In the current course on Teachable, it doesn’t cause an issue until section 3 (Working with Data), because it uses Entity Framework. To resolve this issue, refer here: Enable -migration not working
The next problem is missing Identity libraries, which are required in section 8 (Authentication). Here’s an outline of a great way to quickly get this working. ASP.Net MVC: Change from "No Authentication" to "Individual User Accounts" on existing project - Stack Overflow
Be sure your DbSet definitions for applicationDbContext (IdentityModels.cs).
To be clear in regards to copying/adding files to solution from the “dummy” project over to your live project, I would recommend using the “Add Existing” option in solution explorer, then you can select the files/directories needed and they will be added to the solution. If you simply copy them over to the directory using something like File Explorer, you would still need to manually add them to the solution.