The ATWINC3400 is not supported by Microchip in Atmel Software Framework 4 (ASF4) / Atmel Start, and not supported for use with microcontrollers such as the SAMD51. I recently ported the ATWINC3400 software library to function with ASF4. In this video, I give a brief demonstration on how to use it.
The code for this tutorial: https://github.com/davepruitt/samd_tu...
ATWINC3400 software library for ASF4: https://github.com/Vulintus/ATWINC340...
Microchip support article about choosing an SPI baud rate: https://microchipsupport.force.com/s/....