I definitely found it to be a challenge to deploy an app to a self-hosted Shiny Server about a year ago, having a few years of basic git/cli experience but no hosting/nginx/etc experience.
From the posts above (unless I'm misinterpreting!), it sounds like you may have some trouble following the tutorial due to a lack of git and command line experience. So, you might want to follow git tutorials like this one and/or exercises to get comfortable on remote servers, like the first few stages of overthewire.
In the meantime, if you haven't considered it already, shinyapps.io is very easy to deploy to and has free and paid tiers (edit--ahh, I see now that you had a previous post about this where you already considered shinyapps.io)
Good luck! 