I retried it and it worked fine. When I previously tried it, I had to go through the web installer for some reason. My thinking is that this happened because I had changed all the root Mysql passwords from the default “dietpi”, so NextCloud couldn’t install via the command line, I had forgot that I received an error about this, which I ignored 
I might be alone in wanting to change my passwords from the default but do you think there would be anyway of allowing the user to choose there own admin name user and password? Or if there’s anyway to change it post-install, I just personally don’t feel it’s secure enough for me to have that as the admin login.
Sorry for being so difficult, the automated install is really awesome, the reason I’m not manually installing is because of all the other good stuff you’ve added in, I just wish there was a way to change a few parameters. 
GitHub Issue here https://github.com/MichaIng/DietPi/issues/533