@hsesYou can try archived images. https://armbian.hosthatch.com/archive/rockpi-4b/archive/
5.8 should work. You can then update/upgrade.
@IgorAll rk3399 images seem troubled. I'm waiting to release a video about the Buster media script since no Buster Legacy image works on download page for RK3399. There are enough ways to make it work with either self build, archived or @balbes150 images.
I hope the beast will soon flex its muscles