Per my understanding this SDK driver allows using one TX and one RX message buffer at a time. Thus I think your config cannot be done with this driver.
I can suggest to configure the FlexCAN directly touching module registers. You can refer to this demo code; https://community.nxp.com/thread/433482; modify it to use more MBs for RX function.
I didn't find anything like touching module in datasheet please help how to configure and use this module for Flex CAN.
The link you shared for demo code is not opening,it shows the following error.
Thanks and BR,