Hi Mark,
As the error states, it’s unable to find valid certification path. Option 1 is to run mvn clean compile -U -Dmaven.wagon.http.ssl.insecure=true -Dmaven.wagon.http.ssl.allowall=true -Dmaven.wagon.http.ssl.ignore.validity.dates=true
Option 2 is to download the certs and add to the truststore: mvn clean install -Djavax.net.ssl.trustStore=<path to certificate>