The command is

obj = CloudExport[frames, "GIF"]

To make it loop, use

obj = CloudExport[frames, "GIF", AnimationRepetitions->Infinity]

This will create a private object by default, but you can publish a public copy of it it for anyone to see using

CloudPublish[obj]

When you call Export, the object is placed in the working directory of whatever environment you are in. In the cloud, this will be a path local to the cloud server, which is not the same as the external web address for the object.

Instead of calling Export, try CloudExport. You will get back a CloudObject that has a URL. It will also set the object up with the default access permissions and your code will work if it’s run locally as well as in the cloud.