I tried to create a Volto app within my cloned Github repository github.com/plone/volto following the instructions in the readme file.
I installed yarn and @plone/create-volto-app using npm.
The command create-volto-app myvoltoapp failed with:
Success! Created files for "myvoltoapp" Volto app
Installing npm modules:
Error! Failed to install @plone/volto, try again.