I have Windows 7. I downloaded and unzipped apache-maven-3.3.3-bin.tar.gz.
1) M2 and M2_HOME are under "System variables"
M2 is set to my maven bin folder(ex:C:\Program Files\Java\apache-maven-3.3.3\bin
M2_HOME is set to my maven main directory(ex:C:\Program Files\Java\apache-maven-3.3.3)
2) PATH and MAVEN OPS are under "User Variables"
PATH is C:\Program Files\Java\jdk1.8.0_60\bin; %M2%
MAVEN_OPS set to -Xms256m -Xmx512m
------Things i've tried: restarting, running command prompt as system admin.