Dear Goodnotes4 Developers

How are you?
I am a Goodnotes 4 user from Thailand and I have a question for you. I can't open Goodnote4 after updating my iOS version to 14.6. I have important files in the app and I tried importing them to Goodnotes 5 but to no avail. Is there any way I can get my files and documents back?
Thank you for taking the time to read this and I am patiently looking forward to your reply.

Thank you.
Charles