I'm sorry to have to tell you but you can't use DCG with UP3, as the eventlog logging has been changed to increase online security, so DCG can no longer parse it and you end up with errors.
DCG 3.46 also only supports the stock version of MDS in 4101, what ZUTI built into UP3 goes far beyond that, but since UP3 isn't even final yet Paul wouldn't even start adding compatibility until it's all tried and tested, if at all that is, as DCG is only designed to support the stock game, and I don't think UP3 is going back to the old logging, so, no go I'm afraid. Hades and ZUTI do make the point that MDS has everything you get in coop and more, but I can't see how you can have DCG generated campaigns in an MDS dogfight server, despite DCG having a dogfight mode..
The alternative is to use Dark Blue World, which is actually for offline only, but doesn't include MDS so standard coop mode should work, like stock, but this isn't actually supported.
Standard DCG will work in DBW, but without the mod planes and only if the stock loadouts are still in DBW, so you need to be careful, but then you only need the stock game anyway.
I'm currently working on a DCG fileset for DBW, which is unfortunately proving to be a bit more involved than previously with UP or HSFX, so it works but still has problems, so I wouldn't recommend squad coops until it's all sorted out, as the loadouts are proving to be a persistent problem, unless you test the planes & loadouts you want to use first.
You can find it in the Downloads for DBW section here
https://www.sas1946.com/main/index.php/topic,16680.0.htmlThere'll be another update soon, but you could look at this version for now for testing.
Any pre-DBW campaigns may need to be updated for compatibility as most were made for UP2, and things have changed since then.
A working alternative would be to use HSFX501 for now, as AKD produced a full set of files to enable DCG which are also available here in the Missions/Campaigns section
https://www.sas1946.com/main/index.php/topic,15016.0.html but I think there were also some problems here.
Hope this helps you out, at the moment you're in the middle of an interim transitional phase where UP3 isn't final but probably won't support DCG, DBW is going to version 1.2, and I'm still working on the compatibility files, but this will all be sorted out eventually, DBW is a long-term concept so once everything settles down we should all be set up for good.
The forums are being moved, so currently they're not available, - apparantly they drowned...