I know I'm missing something obvious here. Created a Ubuntu VM, put Java and WebGoat on it but get:

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/owasp/webgoat/server/StartWebGoat has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0
when I try to run it. Environment:

• openjdk version "11.0.18" 2023-01-17
• Ubuntu 22.04.2 LTS
• WebGoat 2023.3 and 2023.4