Hi @karmegancjk,
All of the configuration parameters are described inside the respective driver user manual. Under "C:\NXP\S32DS.3.6.1\S32DS\software\PlatformSDK_S32K3\RTD\Spi_TS_T40D34M50I0R0\doc" you can find RTD_SPI_UM.pdf.
1. SpiBuadrateConfigRef is the reference node used in order to calculate the Spi baud rate.

2. SpiUseBaudrateConfig uses the reference node, SpiCalculatedBaudRate uses the following formula:
SpiCalculatedBaudrate = Function clock / (SpiPrescalerValue * (SpiScaler + 2))
3. You can use the existing example "Spi_Transfer_S32K344" to use as base. Also, chapter 3.6.13 of the previously mentioned file shows how to configure baud rate:

Best regards,
Julián