I am going to suggest overriding the umask on the client machines. Apple has a published article on this here Setting a custom umask in OS X - Apple Support
Basically you want to run this command:
sudo launchctl config user umask 002
The command above will set the octal permissions to 664 for files and 775 for folders. This grants read and write to both the owner and the group of each file and folder created after the command was issues and the machine rebooted.
Permissions on existing files are not altered.
The command creates or edits /var/db/com.apple.xpc.launchd/config/user.plist. Removing the file and rebooting the machine will revert the user permissions to a umask of 022.
Reid
Apple Consultants Network
Author - "El Capitan Server – Foundation Services"
Author - "El Capitan Server – Control & Collaboration"
Author - "El Capitan Server – Advanced Services"
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