I am not allowed to comment to pkyeck's response which did not work for a few people including me, so I am adding a separate comment in continuation to his response:
Basically try to add the variable which he has mentioned in the .profile file if the .bash_profile did not work. It is located in your home directory and then restart the terminal. that got it working for me.
The obvious blocker would be that you do not have an access to edit the .profile file, for which use the "touch" to check the access and the "sudo" command to get the access
touch .profile
vi .profile
Here are the variable pkyeck suggests that we added as a solution which worked with editing .profile for me:
export M2_HOME=/apache-maven-3.3.3
export PATH=$PATH:$M2_HOME/bin