This is a "midi for noob's" question and a complete answer would require writing a book in this reply. To try to keep it really simple, midi requires channels. In Biab a particular instrument track transmits the data on a midi channel between 1-16. Go into options>preferences/midi/channels and it tells you what instruments are on what midi channels. Then your Kurz has to be set to receive the same channels or you hear the wrong instruments. I think they call it multitimbral mode but it's in your book. But wait, there's more. The Kurz has several different banks of sounds and you have to set Biab to transmit the correct bank info. This is in the Biab help file under "patch maps".
To avoid all this set the Kurz to "GM mode" if it has that. I believe it has a GM bank of instruments but you will have to look that up in the Kurz manual. If you can do that, then you're done because Biab defaults to GM. That will get you started but some of the best Kurz sounds are not in the GM bank so that's where the patch map comes in.

When you refer to the Forte DXi and ASIO or MME, that's for software synths, your Kurz is a hardware synth. Two completely separate things. MME/ASIO makes no difference when you're playing a hardware synth but it can with software like the Forte.

If you have no idea what I'm talking about then you're going to have to do some serious reading about midi both in the Biab help files and your Kurz manual and online. You can also do a forum search using the keywords "patch map". There's a lot of treads talking about patch maps and the basic info applies to any hardware synth.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.