I have found an article to begin my journey with latexmk, and this is the article
drewsilcock.co.uk/using-make-and-latexmk. However, I just made a plain file and copied and pasted the whole code (at the page end) into it. Then, I created a Hello World code and configured the compiler to be latexmk, but I got an error
i.imgur.com/5JATKf3.jpg . Can somebody tell me the missing step?