The documentation provided in the jobserver repo is indeed confusing.
Here's the steps I followed to manually build and run Spark Job Server on a local machine.
1. git clone https://github.com/spark-jobserver/spark-jobserver
2. sudo mkdir -p /var/log/job-server
3. sudo chown user1:user1 /var/log/job-server
4. cd spark-jobserver
5. sbt job-server/assembly
6. cd config
7. cp local.sh.template abc.sh # Note that the same name 'abc' is used in steps 8 and 10 as well
8. cp ec2.conf.template abc.conf
9. cd .. # The jobserver root dir
10. ./bin/server_package.sh abc # This script copies the files and packages necessary to run job server into a single dir [ default - /tmp/job-server]
11. cd /tmp/job-server [This is where the files and packages necessary to run job server are published by default]
12. ./server_start.sh
13. Run ./server_stop.sh to stop the server
Hope this helps