The xTuple Updater is a package installer. It is a cross-platform application which connects to your xTuple ERP database and installs xtConnect and other extension packages. The Updater is the same tool that is used for upgrading xTuple ERP databases from one version to the next. It also converts xTuple ERP from one edition to the next (e.g., PostBooks to Standard).
The Updater tool can also be downloaded from GitHub:
Point your web browser to http://github.com/xtuple/updater/release
Click on the latest release, which should appear first in the list
Click on the link for your platform
Please refer to the xTuple Compatibility Matrix if you have concerns about appropriate versions.