Hi gedinson. I would just suggest trying again, the download is hosted on itch.io and it should be a reliable source.
I'm gonna do a quick test as well.
If you go to the itch website (not through sidequest) you'll be able to download the APK directly, assuming you logged in with an itch account. If not, you'll see an option for "I've already paid for this" , which will help you get the file again. If sidequest isn't working, try the direct download (to confirm you've got 100% of the file) and then install manually (drag file onto sidequest logo)
I had that a lot in the start. What I did was change the file type to "all files", or whatever that is besides APK - there's only one other choice. I then changed the file name to not read "APK", but "AP_", just temporarily for downloading it. Not sure if it's a blocker or something, but it seems to work each time. It seems to be applicable to most if not all instances of this weird error.
