I'm not familiar with the way DropBox works on iOS, but if you run Apple's 'Files' app , are you able to see the KAP files? Essentially AngelNav will be able to access any folder that you can access using the Files app.
If not, it may be possible to transfer the files using the DropBox app to regular storage on the dive (eg 'on my phone').
Anyone else on the forum use DropBox?
Bill