File not found despite showing in ls

I'm running 64-bit debian but the file is linux32 could it be related?

It's not only related, but is the direct cause of the error.

When you try to run 32-bit executable on a 64-bit system without support for 32-bit runtime installed, this misleading error is displayed. It is not the ./steamcmd that is missing, but its loader.

For a detailed explanation see the answer under Getting "Not found" message when running a 32-bit binary on a 64-bit system on Unix.SE.

The suggested solution for Debian is to install multi-architecture support with:

dpkg --add-architecture i386 && apt-get update