As I understand your question, you want to buy a MacBook Pro but split the payment for it among multiple sources (in your case, two credit cards). Is that correct?
I think you can do that, as that option should be made available when you purchase a Mac from their Online Store. I'm confused though because you said you already bought the Mac, meaning Apple already secured payment for it.
Now, if you want to use your Apple Card to satisfy another credit card's balance I'm not sure you can do that.
Refer to this note from How to use Apple Card - Apple Support:
* Using Apple Card for a cash advance or transferring balances is not currently supported.
If that doesn't answer your questions though I think you will need to contact Apple and ask.