LaTeX Error: File `fancyhdr.sty' not found.

Hi @tjcnnl1

Is this with a recent TInyTeX installation ? You could try updating to last release.

install.packages("tinytex")
tinytex::install_tinytex()

or reinstalling

tinytex::reinstall_tinytex()

Maybe it will help.

BTW I am on Windows and the document compiles fine for me.