Hello,
There is a SPI_SDCARD demo based on LPC55s06-EVK from SE team, you can refer to it, I have attached it.
"The example code based on LPC55S06-EVK and FRDM-FXS-MULT2-B module board
The LPC55S06-EVK should re-work below items: 1. Shorted JP25/26 by PIN1-2, 2. Removed U24."
BR
Alice