Trying to use MCUBoot for FOTA under SDK 2.8 and build system doesn't see sysbuild.conf afai can tell

I'm running SDK 2.8 and 2.8 Toolchain. I created the sysbuild.conf setting:

SB_CONFIG_BOOTLOADER_MCUBOOT=y

and put it in the application folder (per this support request:  RE: Issue with MCUBOOT enabling) and it wasn't recognized. I got the error "was assigned the value 'y' but got the
value 'n'. Check these unsatisfied dependencies: BOOTLOADER_MCUBOOT (=n)".

I then read another post where the reply stated that I should put the sysbuild.conf in the build folder. So I tried that, and also tried in the subfolder under build with the project name ("l8_e3"). All resulted in the same error - BOOTLOADER_MCUBOOT dependency is not set to y. I tried checking the documentation at the links provided above https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/app_dev/bootloaders_dfu/mcuboot_nsib/bootloader_adding_sysbuild.html, but it is not clear about the location of sysbuild.conf, just that it needs to be created.

Just to make this clear to others traveling this path who tried to use the intermediate academy exercise (ncs-inter\v2.6.2-v2.5.2\l8\l8_e3) and found that 2.8 is not yet supported, could you lay out exactly what and where changes must be made to upgrade that sample to 2.8?

Thanks for any input! Appreciate this forum so much!
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