CodeIgniter 4 by composer and deployment

Hi everybody,
I must say that although I have been in love with CodeIgniter for many years, I am a beginner. So please be patient with me ;-)
I am trying CodeIgniter 4 into development environment on my PC to understand the differences with CI3 and to evaluate, in the future, the porting of my web application. I am not being very experienced with repository, Git and composer: I've always preferred manual installation; but now I'd like to better understand the potential of composer.
In the local machine I installed, as in the guide, CodeIgniter 4 through composer, together with Translations and Myth:Auth by @kilishan. Everything works like a charm! :-)
But what I would like to understand, now, is how to deploy my web application on the production machine (Ubuntu server on which currently are present Apache, PHP, MySQL and the web application CI3) in a correct way (I don't think it's copy the whole root directory...); I know that I should study and understand a bit composer... But could someone give me a quick help? In the CI 4 documentation is explained very well how to install it all, but I didn't find anything about deploying it in a production environment.
Thank you for all your fantastic work, which I have been silenty appreciating for years, and thank you in advance for any help you can give me :-)
My best regards