Assuming you have received the custom report by email and have saved it to your Downloads folder, follows these instructions to install a new or updated report:
1) Select the "Reports" ribbon tab
2) Open the Custom reports window
3) Click on the "Import Report definition" report button
4) Locate the report script file emailed to you:
5) The report is now imported
6) Optionally, right click on the report name to add it to your favorites: