Found no description of how exactly people vote with Agora https://agora.vote/ https://agora.vote/: do they come to a place and press a button or do they downlo

Found no description of how exactly people vote with Agora https://agora.vote/ https://agora.vote/: do they come to a place and press a button or do they download an app(or go to a web page) and press a button? Either way, I can't see how fraud is prevented even with a blockchain in place.