If it is a slightly older device, you may also need to update Google Play itself, I have seen this once before. In which case you should open Google Play, go to Settings > Info ... find the build number of the App and click on it 15 times in quick succession...this should cause a popup which either reads "Google Play is up to date" or it will initialize an update to Google Play automatically and install it. So you should make sure you are on an active and stable internet connection before doing this.

I hope this helps. I personally am still unable to log for unrelated reasons. Very depressing tbh.