Instant alerts are sent out when builders share files or photos with clients on CoConstruct, however they are not sent to the builders when clients upload them.
Trade partner uploads are a different story. Based on their settings (Main Menu > Settings > Personal), builder side users may receive an instant alert when a trade partner uploads files or photos to a project.
The instant alert email will show you the location of the document, name, and project, as well as who uploaded the file. You can also download the file directly from the email.