Did you try clearing the game cache & refreshing the app?
Otherwise, only SUPPORT can help you
Open your game settings (cog in upper corner of game window.) Take note of your Player ID# & then click the SUPPORT button. Once on the linked page, scroll PAST the white search🔍 box & choose a category to begin the form. If no category options are listed, email them instead:
PS: Had a thought...if by chance you played this Event previously, and already got the 1st level of the Achievement, the game just picks up where you left off. You wouldn't get the level 1 rewards again.