Regular Arma 3 DLC makes use of our Content Licensing system. This requires every Arma 3 player to have all DLC data installed, even if they do not own the DLC. The main benefit is that players who do not own certain content can still play together with those who do own the additional content. For Creator DLC we have decided to make it optional to have the DLC data installed. This is mainly to avoid that a regular Arma 3 installation would require a lot more additional hard-drive storage. The second reason is that a Creator DLC's theme or setting might be very different from regular Arma 3, and not everyone might want that to be visible in their game. To help mitigate this last point, we will also be updating the Arma 3 Launcher to make it possible to have Creator DLC installed on your PC, but also have the option to launch the game without particular Creator DLC packs loaded.
You need to own Creator DLC and have it installed to be able to join a multiplayer server that makes use of it. If you try to join a server without having the requested Creator DLC installed, you will receive a notification that you are missing content that is needed to play on the server. For more information please also see the previous question regarding the optional installation of Creator DLC.
Beides aus dem offiziellen FAQ hier (Link).
Im Endeffekt ist der DLC also eine bezahlte Mod. Ob man das gut oder schlecht findet, sei mal dahingestellt, aber die Nutzung auf Publicservern ist dadurch leider ausgeschlossen.