All relevant data will be saved in a MongoDB (NoSQL database) and on the hard drive.
The simplest way to backup the MongoDB data is to use rsync or cp. The docker-compose.yaml creates a volume in the folder ./mongo/volume. The whole folder is relevant for the backup.
More information MongoDB backup strategies: MongoDB Backup Methods
By default all job files will be saved under ./jobs. The whole folder needs to copied by rsync or cp.