Prototypes can be shared via public links, so people can access them without an Antetype Cloud account. Public Links can only be used for viewing, not uploading/editing.
If you want to your prototype, the public link has to be activated.
To create a public link, choose the entry from a prototype card's menu.
In this dialog, activate the link by changing setting to "can view". You may also add a password and set an expiration date afterwards.
In addition set the start screen, the initial visibility of the tool bar and specificaiton inspector or activate the resize mode.