Open terminal and navigate to the directory where you downloaded. If user pi run sudo chmod +x piardopc This will make it executable.
If you are running direwolf you will have to stop it before proceeding. This tripped me up at first. sudo killall direwolf
I am using a SignaLink to connect the RPi to my radio. The SignaLink is listed as card 1 when I run arecord -l (Note: That is a lower case L) If yours is different, you will have to change the plughw:1,0 to match your sound card in the next command for it to work.
piardopc is a command line program so open terminal to where you downloaded and run ./piardopc 8515 plughw:1,0 plughw:1,0 Where 8515 is the port and plughw:1,0 is my SignaLink. Leave this terminal window open and open your web browser. Navigate to the Pat GUI
At this point you should be able to make an ardop connection from within pat's web interface
I'm no linux expert but this worked for me. If you run into trouble with piardopc starting, check this group -
https://ardop.groups.io/g/users/topics Hopefully it helps get you started as well.
73,
KM4ACK