Install
aria2c -s10 -j10 https://mirrors.tuna.tsinghua.edu.cn/CTAN/systems/mac/mactex/mactex-20161009.pkg
The MD5 is: 5158d5e883dee3f17c7a98f6012706ed
ref: https://www.tug.org/mactex/mactex-download.html
Documents
https://www.sharelatex.com/learn/Main_Page
https://en.wikibooks.org/wiki/LaTeX
Online LaTeX
https://www.sharelatex.com/
https://papeeria.com/
http://www.hostmath.com/