'audio interface' - what do you mean by that?
These days, the term usually means an external box with line and/or mike level inputs, connected to the computer by a USB cable. You hook the live level outputs of the 970 to the line level inputs of the interface and select the interface as the source for recording in whatever software you are using. Should be as simple as that. I have a Roland UM One MkII interface that does that, but I also have a simple lead with a built in USB interface. Two 1/4" mono jacks go into the keyboard, USB plug goes into the computer or laptop. No drivers required, just plug and play. And finally, I have a USB mixer where I can plug organ, keyboard and sound module in, adjust their volumes and take the stereo mix to the computer via USB. Again, it's plug and play.
All three methods work just fine.
If you're just trying to run the line level outputs into the mic socket of your computer, then don't expect good results.