The script is available for download from https://gallery.technet.microsoft.com//How-to-make-lower-level-96a5d485. You can also use Microsoft Script Browser for Windows PowerShell ISE to download the sample with one button click from within your scripting environment.
This script will grant Admin Role and Full Access Permission to the User Mailbox.
This script is to help Exchange Administrators to grant Admin Role and Full Access Permission via PowerShell.
You can find more All-In-One Script Framework script samples at https://aka.ms/onescriptingallery