You need to customize DDR controller configuration parameters according to the DDR on your custom board.
You need to use QCVS tool to calculate the initial DDR controller configuration parameters, then use DDRv tool to connect to the target board to do validation and optimization to get the final DDR controller configuration parameters.
Please refer to https://www.nxp.com.cn/docs/en/user-guide/QCVS_DDR_User_Guide.pdf
If there is SPD on your custom board, please use reading from SPD to generate QCVS DDR project.
If no SPD, please create QCVS DDR project with the default configuration, then modify the properties according to your DDR datasheet.