Keep in mind the GameJolt login has nothing to do with your saved game - the only thing logging in does is allow you to submit your scores to the leaderboards and earn trophies. Your saved progress is stored locally on your computer, even if you are not logged in. Troubles logging in may be GameJolt API issues, but you should still be able to save even if not logged in. Your progress is local, so if you play in the browser, the Continue button will only appear when you are playing in the browser on that same computer.