Query to correctly generate the gebers

[Serhi0]

Hello, I have problems with gerbers. I download the project and open it in kicad 6.
I run DRC and get various errors.

I follow these instructions:
https://support.jlcpcb.com/article/194-how-to-generate-gerber-and-drill-files-in-kicad-6

With the gerbers generated, I open them with kicad's gerber viewer. I get this:

So that several layers are incomplete. What am I doing wrong?

[Kristoffer-Martinsen]

I also get the same errors. One of the errors that I get mention something about the version of kiCad so I'm guessing that something has changed between versions. I don't know if there's anyone who know a fix?