We don't have any control over the way Google Play installs updates. This normally means that Google had some sort of issue sending the updated Firefox to you. Google keeps a list of known issues at https://support.google.com/googleplay/known-issues/1319135?hl=en

Thanks for your reply Deleted firefox apt from Playstore and installed it again but same mistake Installing firefox beta works without problems but i cannot sync with my firefox on my laptop