You can add a public voting round for your program in Evaluation > Rounds by creating a new evaluation round via the Add round button and selecting Public (anyone with a link) in the Evaluators setting.
Every public round you create has its own link, which is provided under Portal URL.
By choosing the Public evaluators option you allow anyone who opens the link to use their Google, LinkedIn, or Facebook social profile to log in and cast their vote for the applications shortlisted in this particular evaluation round.
When creating your application forms (Settings > Forms), most fields you add to a form have the Data access option, where you can set who gets to see this field. Fields marked with "Admins only", or "Admins and Judges" will not be visible to the public during a public voting round.