Hello,
I own a CA98 and this is the setup I use.
Get a USB cable so you can connect your piano to your laptop - I have a MacBook Pro 2017, so I specifically use a USB-B to USB-C cable. Next, I use a 3.5 mm audio cable so I can connect the headphones output from the MacBook Pro to the aux input of the piano. Go to the options menu in Pianoteq so the Audio Output is sent to 'Built-in-output'. Finally, you will have to turn Local Control OFF inside the piano's settings menu so that the internal SK-EX rendering is turned off. Adjust the aux input volume knob on the piano to an appropriate level.
Sometimes I connect laptop to an audio-interface (I use Scarlett 2i4), and then use RCA to 3.5mm audio cable to connect the audio-interface to the piano's aux input. This method, I feel, provides better SNR since the audio-interface has better DACs compared to my laptop.
Surprisingly, for my basic Yamaha P-125, all I need is the USB cable! Somehow the Yamaha can send both MIDI inputs to the laptop and receive audio data from the laptop. Seems like the CA98 can't do this, which is why I use audio cables and the aux input.
If someone has a cleverer way, please let me now!
But, I hope this helps.