How can i Watch yupptv on apple tv???

Welcome to the Apple community.

You can only view the features that are included with the Apple TV software.

You may be able to view this media, if they have an app that can use AirPlay or a website that that is AirPlay enabled.

Apple wants you to buy 2 devices, a) apple tv b) iphone or ipad.

You install the yupptv app on iphone or ipad, connect your tv to apple tv device, then do airplay in your iphone or ipad connecting to a common wifi ( appletv and iphone/ipad). Really if you are looking to cut cost, appletv is not a right option, unless apple allows to install any app on appletv similar to iphone/ipad. Also the quality of display thro airplay on a appletv device is not very good.