To install libmtp, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install libmtp
To see what files were installed by libmtp, run:
port contents libmtp
To later upgrade libmtp, run:
sudo port selfupdate && sudo port upgrade libmtp
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.