Hi chenxikean,
Do you mean mdk MKL15Z32VFM4 DFP?
If yes, please download this dfp from the keil side, and install it, you will find the related chip:
https://www.keil.com/dd2/pack/#/third-party-download-dialog
under keil item, you will find the KLXX series:

Download it and install it.
You will find it in your MDK:

Wish it helps you!
If you still have questions about it,please kindly let me know.
Best Regards,
Kerry