Is there anyone using EZ Key in a Dorico environment? Is it only available in a DAW?
EZKeys can both work as a simple piano instrument, as well as follow Dorico’s tempo in its own built-in sequencer, giving you access to all the magic stuff… 
Dorico cannot at the moment transfer tempo changes, so I don’t know how this would behave, I’ve used plugins that follow Dorico’s tempo only with steady tempos.
And you can drag loops into Dorico’s play mode and have it nicely notated!
B.
Thank you for your advice. Do I need a plug-in to change the tempo? What kind of plug-in is it? I would be grateful if you could let me know!
EZKeys (and other plugins that can follow the tempo map of a DAW, like Superior Drummer 3, Synthesizer V, EZBass, …) can follow Cubase for example just fine, but Dorico just doesn’t transmit changing tempo just yet. Apparently the tempo is set at the beginning of the piece, and then EZKeys´ timeline will just play at that tempo regardless what Dorico is doing.
There is no way at present to have those plugins react to ritardandos, tempo markings and the like. The team has expressed a desire to have this functionality working “in the fullness of time”… 
B.
What is the plug-in that you mentioned in your previous post that follows the tempo of Dorico only at a certain tempo? If it’s not there, it won’t sync! Also, when using EZ Key, can you paste data into a Dorico track like you would with a DAW?
It’s EZKeys itself, and not following tempo changes is a limitation of Dorico, not the plugin!
Yes, you can drag/drop MIDI from EZKeys into Dorico’s Play Mode.
B.