Some of the packages needed by PX-MBT are distributed through jitpack. If they fail to download (e.g. maybe jitpack site is down) you can install them manually.
These are the packages distributed from jitpack. The file pom.xml of PX-MBT specifies which version it usues.
In case package X fails to download from jitpack, download X manually from the link above. Unzip it, and do mvn install from X's directory.