uDock can be activated (triggered) by a key stroke, mouse event or touchpad gestures. Depending your macOS version, uDock can require the Input Monitoring permission to receive key strokes, mouse buttons or the touchpad gestures. In macOS Big Sur, the Input Monitoring permission is required for "Touchpad Finger Tap".
Open System Preferences, click Security & Privacy, then select Privacy tab:

Then click the lock icon at the bottom to make changes. On the list click "plus" button to add uDock:

Select uDock and press OK button:

Input Monitoring grants permissions for a specific version of the application. When updating uDock, you will probably need to replace the uDock application listed in the Input Monitoring tab: select uDock in the list, hit the minus button and add the new uDock version again.