Peertube has a very strange system for creating the password for the admin user and unfortunately it doesn’t work.
This command will allow you to set the root password and log in.
cd /var/www/peertube && NODE_CONFIG_DIR=/var/www/peertube/config NODE_ENV=production npm run reset-password -- -u root
Keep in mind that you won’t actually see any characters appearing on the screen as you type the password. You won’t even get a representation of each character.