The plugin emulates a Mackie Control Universal Pro, and most buttons, faders, V-pots and displays are available. The channel strips, the displays and the transport section are fixed in that they are the same regardless of which layout you select (i.e., which DAW you connect to). Various layouts are available for the master section (the right side of the Mackie Control). These layouts give the buttons the correct names for the DAW (hopefully) and should make life a bit easier if you are used to a specific layout. A generic layout (i.e., the layout printed on the Mackie Control) is also available.
The Mackie Control protocol is very chatty, and a lot of information is sent from the DAW to the Mackie Control (i.e., the plugin) to keep it up to date with the correct state for all buttons, LEDs, faders and so on. But... there is no (known) command the plugin can use to request the "current state", which means that the plugin might initially show an incorrect state if Stream Deck is started after the DAW.
The plugin will receive and keep track of the state for all the functions of the Mackie Control, even for functions currently not assigned to any button on the Stream Deck. If you, e.g., have Mackie Control buttons in several Stream Deck profiles or folders, the plugin will monitor the state and provide the buttons with the correct state when you switch profiles or folders.
Please note that the Mackie Control protocol requires that the midi ports used in the communication are exclusively dedicated to the Mackie Control - no other devices or plugins should use the same midi ports. The used Midi ports in the DAW must not be connected to anything other than the Mackie Control receiver. If you have a real Mackie Control, it must have midi ports of its own.