Thanks for the help, but I am still having issues.
After figuring out that I needed to also download the kernel, and put it into boot, I managed to get things together, and all the files are where they should be, but now when I try to boot, I get:
switch to partitions #0, OK
mmc0 is current device
** File not found var/Image **
** File not found var/armada-3720-community.dtb **
Bad Linux ARM64 Image magic!