You can go directly to USM's CloudLibrary page from a computer and sign in using your Library barcode (218... or 250...) from your USM ID card.
Or go to the CloudLibrary site for compatible devices and download the CloudLibrary app. When creating an account, you will be asked to:
Select your Country: United States
For Barcode issues call 207-780-4270.
You can bookmark USM's CloudLibrary page on your computer.