What type of phone do you have? I have a Samsung Galaxy S22ultra and it works fine when the app is in the regular location on the phone. However if I have the app in the Secure Folder and try and download it doesn’t work (or goes somewhere that can’t be found). I had reported this bug awhile back but no fix as of yet. Other Lemmy apps don’t have the same issue.
I think vote up is to “like” a post and down vote to “dislike” a post. If the intent is to use down votes to prevent spam that is what a report button would be for.