How to sync just to SD card on ZTE Cymbal Z-320?

I’ve ran in to kind of a snag when using Windows Media Player to sync MP3 files to my ZTE Cymbal Z-320.

I have an 8GB SD card installed.

When I plug the phone in the computer I can go into Windows File Explorer and see both the internal and SD card memories on the phone.

The first time I synced with WMP it did go partially to the phone and then stopped. I disconnected the phone and tried again and it didn't recognize it as a device it had previously synced to, so I had to set it up again. The good thing is it did sync to the SD card

This happened again so I restarted the computer. This time it synced to the phone's internal memory and not the SD card. The phone's memory is very small so fills up quickly.

I’ve tried erasing and restarting several times but it keeps syncing to the phone’s memory now and not the SD card.

Any idea of how to get WMP to sync just to the SD card and not the phone’s memory?