DigitalExperienceManager-CommunityDistribution-7.3.1.0 starts with error 'Cannot set maven executable to mvn, please check your configuration'

Question

I run \'java -jar DigitalExperienceManager-CommunityDistribution-7.3.1.0-r59490.jar\' to start it, and I find this error in catalina.out:

2020-12-16 19:1