Rock64 Debian 11 (Bullseye) install problem

[ju0n]

If you used the Debian Installer, you won't have U-Boot installed. Because the Installer is generic for all supported Boards, they do not install board specific U-Boot.
You have to install U-Boot in order to get Debian working.
Two options, either build U-Boot on device after Installer has finished and flash the SD-Card with U-Boot or use the files Debian provides:

/usr/lib/u-boot/rock64-rk3328/u-boot.bin
/usr/lib/u-boot/rock64-rk3328/idbloader.img

they are part of the package "u-boot-rockchip".

Hi,
I'm stuck just in this place. Can you help me to make my debian SD card bootable? I'm newbie and dont konw how to proceed with  two options you suggest.
Thanks in avance