Show window for transfering and extracting files in KDE Plasma 5
KDE Frameworks 5 and Plasma 5 notifications
As default the plasma 5 desktop is showing copy progress in the task buttons and in the notifications:
Task manager setting: "Show progress and status information in task buttons"
Notification Settings: "Track file transfer and other jobs"
If both (task button progress & notification transfer) settings are disabled the traditional file transfer window will be shown:
Plasma setting changes may need to restart the plasmashell - logout and login.
KDE Forums: Dolphin not showing native file transfer dialog - https://forum.kde.org/viewtopic.php?f=224&t=135264