It could also be that you're doing something wrong, but I can't help you, if you don't explain your steps... Oh! Why don't you try out another file manager? I use the Es File Explorer. Or press in the joiplay app on [ + ] to add a game that way? Also, make sure to extract the files first. Why don't you send a screenshot yourself, we could even talk on Discord or so.
Unless you have an iPhone, there should be no reason why it won't work.