Hi @akift ,
Your board is your customer board with the RT1064, not the NXP MIMXRT1064-EVK board, right?
If your own board, what's the debugger you are using now?
Do you test the RAM project at first, eg, you test this demo:
SDK_2_15_000_EVK-MIMXRT1064\boards\evkmimxrt1064\demo_apps\led_blinky

Please run the simple code in RAM at first, whether that works OK?
If it works OK, then deselect the Link application to RAM, and test it again whether you can download to the internal flash or not?
The default code is downloaded to the internal flashloader.
Wish it helps you!
Any updated information, please kindly let me know.
Best Regards,
Kerry