You can not access the maven central repository on the internet. The information is a bit vague so I would try all of these steps as a check, you may well have already done some.
Start by downloading maven from http://mirror.vorboss.net/apache/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.zip
Unzip it somewhere, then assuming your're on windows
1) set an environment variable M2_HOME to point at the unziped folder.
2) add %M2_HOME%/bin to your PATH environment variable
3) go to your home directory (probably C:/Users/????? and create a .m2 folder
4) move the settings.xml file from the maven unzippped/conf directory to the directory created in step 3.
5) you may have to set the proxy element correctly in your settings.xml file (see here for details)
Check all is working by doing:
greg@greg-XPS-13-9360:~/work/local-repo$ mvn -version
Apache Maven 3.3.9
Maven home: /usr/share/maven
Java version: 1.8.0_161, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-8-oracle/jre
Default locale: en_GB, platform encoding: UTF-8
OS name: "linux", version: "4.4.0-112-generic", arch: "amd64", family: "unix"