By default, the virtual mouse executes a short left click when 
pressing the play button. To drag an item, however, you'll want the 
left mouse button to stay pressed.

To achieve that, select the action "Hold left button" for a button of 
your choosing at RB Preferences > Mapping > Virtual Mouse. Then, when 
you use that button the first time, the left mouse button is pressed 
and will stay pressed. When using that button the second time, the 
left mouse button is released.

Best regards, 
Felix Schwarz