According to the doc section regarding automatic installation (using Installatron) I'll be able to use custom fields so customers will be able to choose their database user/password, directory, site name, etc. But it doesn't mention admin username/password.
If there is no admin username/password installatron seem to install the script using the cPanel username and password which is not a good solution regarding security. Reading the documentation for Installatron API it should be possible to use both username and password.
Shouldn't customers also be able to choose their username and password using automatic installation? I don't really see the point of letting customers use custom database usernames while not being able to choose their login username in WordPress (as an example). Most people would probably prefer to choose the username and password to log in rather than the database.