Follow instructions at Aspire Registration and Licensing
Maven will try to use the settings.xml file it finds under your local $HOME/.me directory (or ~/.m2), so if there isn't yet a $HOME/.m2 folder create it:
$ mkdir ~/.m2
Now download settings.xml and copy it under $HOME/.m2
$ cp ~/Downloads/settings.xml ~/.m2/
Now edit your $HOME/.m2/settings.xml to include your credentials (registered email and password, see Aspire Registration and Licensing):
<settings> <servers> <server> <id>stPublic</id> <username>[USERNAME]</username> <password>[PASSWORD]</password> </server> </servers> ...