If you are absolutely sure you have connected your device to Facebook or Plarium ID and know the credentials delete the entire game than do a soft reset of your device.
After that redownload the game files and let it also download all assets while in the game before moving to another screen. That should fix most local issues. If you are not sure if you have connected your account *Do not delete anything* and wait for official support.
I would highly recommend stating your device model, and mobile operating system version so support staff can take a further look.
For help with finding the information some suggestions below. (replace hxxps with https)
Android: hxxtps://www.howtogeek.com/347761/how-to-find-out-what-model-of-android-phone-you-have/
iOS: hxxps://support.apple.com/en-us/HT208200/
Hopefully you can continue your event soon again.