The thing is, we can't do anything as hosting is managed by Itchio.
I only remember one player having the same issue, it was downloading the file as com.bin i think (on a samsung maybe). Downloading and renaming it with file manager worked for this user.
I don't know if there's something similar as right-click/save as on your phone, it might help.
If you have a pc you can still dl the apk package on your pc and transfer it to your phone.
Sorry we can't help more....