When installing an Umbraco package you should use the same caution as when you install an application on your computer.
A malicious package could damage your Umbraco installation just like a malicious application can damage your computer.
It is recommended to install from the official Umbraco package repository or a custom repository whenever it's possible.
<%= umbraco.ui.Text("packager", "chooseLocalPackageText") %>
This repository requires authentication before you can download any packages from
it.
Please enter email and password to login.
Please note: Installing a package containing several items and files can take some time. Do not refresh the page or navigate away before, the installer notifies you once the install is completed.
All items in the package have been installed
Overview of what was installed can be found under "installed package" in the developer section.
Uninstall is available at the same location.
<%= umbraco.ui.Text("packager", "packageUninstalledText") %>