We made the app folder Read Write for all
I assume it is faster to use your tech support for this, as it seems to me that you are using old/legacy settings. Without checking your application this is only guessing and all I write could be totally wrong. so the following text could describe your issue - but could be also be very wrong. In that case, please contact tech support.
My first check would be your compatibility page to see if
Use new architecture for application deployment
Then, after a test launch, I would check if the file
~/Library/Application Support/mybestapplication/lastDataPath.xml exists and if the content is correct.
For the next launch, the application should use this file to find the last used data file.