Seafile server on arm64 (aarch64). - WORKING

When you say

“So… installing cross libraries and some armhf libs by hand”

created symlink to the ld.linux-armhf.so.3 and also libselinux1 on a common place and updated LD_LIBRARY_PATH:
export LD_LIBRARY_PATH=/usr/arm-linux-gnueabihf/lib/:/home/seafile/lib/arm-linux-gnueabihf/

can you please provide the details? I am struggling to make it work on my arm64 (odroid-c2) device.