To install mod_mono, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install mod_mono
To see what files were installed by mod_mono, run:
port contents mod_mono
To later upgrade mod_mono, run:
sudo port selfupdate && sudo port upgrade mod_mono
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.