SharePoint folder and sppkg file

[jsoriasanz]

Hi all.

I am trying to test the react-command-document-preview development on my SharePoint Online but I can't compile it as the "SharePoint" folder with the manifest and the ".sppkg" file is missing.
This is the link to the application:
"https://github.com/pnp/sp-dev-fx-extensions/tree/main/samples/react-command-document-preview"

Do you know how I can generate this folder or someone can upload it?

I have tried with a SharePoint folder from another application and I can compile it but the development does not work in my SharePoint Online.

Thanks to all.

[jsoriasanz]

Can someone help me with this?

[jsoriasanz]

I have managed to compile the solution and get the sppkg file but it does not work correctly when loading it into applications.
When selecting an item, the SPFx does not work and the button does not appear in the top navigation menu. Any ideas or someone who can provide me with the correct .sppkg file?
Thank you very much.