Did you read and follow the readme file when you downloaded the image?
Login: repeater
Passsword: allstarlink
SSH port: 22
User repeater has sudo privileges (sudo -s)
There may have been updates to the operating system and AllStarLink since this image was built.
Run the following commands after the first time you boot.
sudo apt-mark hold raspberrypi-kernel-headers raspberrypi-kernel
sudo apt-get update
sudo apt-get upgrade -y sudo reboot
at the # prompt run "asl-menu" to setup your node.
Marshall - ke6pcv