Hmm, I don't know, maybe..?
I didn't have to do that when installing it on a fresh VM or natively on my laptop (fresh install) when that still worked, both of them had Ubuntu 20.04 LTS 64-Bit installed.
And just to be clear here, the README does have the ":i386" part on all listed dependencies in case this is part of what you mean.
But that being said, I might add the "sudo dpkg --add-architecture i386" part explaining that this may have to be run to enable i386 architecture in the README for the next version.
Thanks again for the information/feedback. :)