You will receive an activation email from your administrator. It will contain a link to create your account password. Setting your Passages account credentials will activate your account. The activation email also includes helpful links to the Passages Help Center and User Guide.
After creating your new password, you will be directed to a page where you can download the installer for Passages. Select the installer appropriate for your device and download to your machine. After downloading the Passages installer, open the package to begin the installation. For Windows users, the file will be named PassagesSetup.exe; for macOS users, the file will be named Passages.pkg
You can find further instructions for the Windows installer here and the macOS installer here.