Pukiwiki met permission error

Hi. I’m trying to setup pukiwiki on fly.io.
With Flyctl I deployed, but now having trouble.
After first deploying finished and opened my app, It says "Runtime Error"and shows berow.

Runtime error

Error message :

Directory is not found or not writable (DATA_DIR)
Directory is not found or not writable (DIFF_DIR)
Directory is not found or not writable (BACKUP_DIR)
Directory is not found or not writable (CACHE_DIR)

It looks like I have to check something about permission. but how can I fix it?