Problems starting Magnolia on Linux usually result from incorrect configuration (or complete lack of) the Java runtime and SDK (Java 8 Standard Edition).  Because Magnolia requires compilation of generated code, the Java SE SDK must be installed (not just the Java runtime).  Moreover, environment variables related to Java need to be set.  See articles here and here for additional information.  If Java is correctly installed and configured, you should be able to start Magnolia from a command prompt by navigating to the folder in which Magnolia was uncompressed, and entering the command: “java -jar Magnolia.jar”.