Songs I transcribed using lilypond that can generate midi files and pdfs
To generate outputs, download and install Lilypond, it is a compiler that generates pdfs and other artifacts from the markup language in the .ly files (http://lilypond.org/download.html). Once installed, right click one of the .ly files and click Generate Pdf and it will generate the pdf, a log file, and any other artifacts (such as midi files) that are configured within the .ly file.
I also recommend downloading Visual Studio Code and the extensions VSLilyPond, LilyPond, LilyPond AutoComplete (Commands & Keywords), and vscode-pdf. You can configure VS Code to compile the .ly file upon saving as well as a bunch of other great features to improve development experience.
A tutorial for how to write Lilypond files can be found here http://lilypond.org/doc/v2.20/Documentation/learning/index.html