Right now, uploading photos to make the four new synth types is limited to the website only.
You can upload photos from any desktop, laptop, as well as some tablets - it doesn't matter if you use Windows, MacOS, or Linux.
You can also view the synths in Internet Explorer 11, or any up to date full version of Firefox, Chrome, or Safari because the new viewer is written in WebGL to use your computer's GPU. Most mobile browsers don't yet have WebGL enabled yet, though.
The Photosynth team has said on Twitter that they do plan to eventually add the ability to upload photos for synths from their mobile apps (instead of only the stitched panoramas that they offer today) https://twitter.com/photosynth/status/411224616103706625 but that is not ready yet. That is why this is a beta or preview. It is a sign of things to come before everything's finished (even the new website).