Your question can be reformulated like this:
> Want to make your Boeing 777, at the moment know how to hammer nails, you need to learn?
1. The project example that you gave one person can not do, accept for the original. Judging by the dates in the footer 2014-2019, his sawed 5 years. I don't know how many people are working, but even if 10 people is 50 man-years.
2. Start small. To begin to examine how, in principle, written in the web system how HTTP works, how to operate databases such as mysql.
3. Learn to decompose tasks.
there should be private offices
This statement literally means nothing, except that there must be some separation of access by users.