Having the exact same Problem here.
The problem seems to be that spacedeck.nexe.bin is a x86-64 binary and thus incompatible to the Raspberry Pi 4 using Raspberry Pi OS 64 on ARM64 / aarch64.
sudo file spacedeck.nexe.bin
spacedeck.nexe.bin: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=2f939e828e5332cd3be98272bedfe905c9f029a7, with debug_info, not stripped
@nextcloud Any chance you could provide a ARM64 version of whiteboard_integration?
Best regards
Thomas