As the "other Tom" has said you can use the app without an account there is just a warning message telling you that if you do your progress is not backed up online.

I actually shipped without this message at first and realized by talking to non technical family and friends that some people might not realize the implications and didn't want someone ending up in my support email 1 year after buying the app telling me they had lost all their data.

I was actually happily surprised that you can continue without making an account