File transfer - donwload file not working if directory already exists

I am trying to download PDF file in android, using File and File Transfer plugin for the same. Its working fine on android 7. But Its giving issue on android 8 and 9.
Scenario on android 8 and 9 -
1 - Install app
2 - Check for external storage permissions.
3 - Create one directory in externalRootDirectory
4 - Download PDF file in this directory.
5 - When directory is not exists and we create it its working fine
6 - Reinstall app and try above steps. In this case directory is already exists(created by first app). Its gives me error permission denied.

Struggling for this from 2 days. Unable to find any solution. Please help.
Thanks in advance.