@Filip Hi. To my understanding it should work, although Pencil2D is a portable app, so I think for macOS you have to still drag the .dmg it to the apps folder and since it is not a signed app you have to open it by right clicking and choose the “open” option otherwise it won’t open.
If trying that out still doesn’t open the program, then I’ll ask one of the devs to see if they can help us here. To be quite honest it is possible that the requirements have gone up and we don’t have control over that unfortunately. We’re trying to look for alternate solutions to at least provide support for 10.8 and above but it seems (to me at least) to be a very difficult task.