Okay...I have not used the app (and I use Linux anyway), so this is just going off of the itch page. With that said:

The page doesn't actually show any collages made in the program. It has a YouTube video, but it's not a video of collages, it's a video of giving the app your e-mail address and making a login. Even if I really wanted a collage and really didn't want to make it myself, this would be an instant nope from me. An itch app shouldn't need my personal information.

Looking at the YouTube account, there's a different video of a collage being made, and...this doesn't look good at all. There's a massive amount of negative space. The photos are too tiny to even be visible, and they seem to just be interspersed completely randomly, with random sizes and no kind of aesthetic care for things like color groupings. The sheer amount of photos it'd take to fill out this bear, which again is mostly just negative space, makes for a ton of redundant photos.

If you search the Internet for collages, none of them look anything close to that bear, and there's a good reason for that. The basic ones use filled-in silhouettes, not these awkward jagged lines made up of arbitrarily sized rectangles. The impressive ones use the colors of the photos to assemble an entirely new picture, or they juxtapose the photos in some interesting way that it'd take an artist to do. (Searching the Internet for collages also turns up a ton of other collage generators, which is also a thing you'd have to contend with. I haven't used any of those, either, though, so I can't really compare them.) I'm sorry for the negativity, but I just...don't understand who this is for.