Cloud Access section is in the 

Profile

 page.

Any storage credentials (S3 for example) are only stored on the client side (never the trains-server), this is the reason we need to configure them in the trains.conf. When the browser needs to access those URL's (downloading an artifact) it also needs the secret/key, it automatically display a popup requesting them, and will store them in this section. Notice they are stored on the browser session (as a cookie).