Previously: business use typically comes with expectations that tend not to align well with consumer grade products (specifically: availability and performance).
Edit: Turns out the answer is yes, no commercial use.
1.2 Using Your Files with the Services. You may use the Services only to store, retrieve, manage, organize, and access Your Files for personal, non-commercial purposes using the features and functionality we make available. You may not use the Services to store, transfer, or distribute content of or on behalf of third parties, to operate your own file storage application or service, to operate a photography business or other commercial service, or to resell any part of the Services.
Edit: Turns out the answer is yes, no commercial use.
https://www.amazon.com/gp/help/customer/display.html?nodeId=...
1.2 Using Your Files with the Services. You may use the Services only to store, retrieve, manage, organize, and access Your Files for personal, non-commercial purposes using the features and functionality we make available. You may not use the Services to store, transfer, or distribute content of or on behalf of third parties, to operate your own file storage application or service, to operate a photography business or other commercial service, or to resell any part of the Services.