It's on the old GitHub, somewhere on the
releases page.
Alan never released binaries on github. The only thing you will get there is the snapshot of the source for that particular tag.
My cold storage laptop is still running that and I want to do an offline transaction, but can't do that with the newer version installed on my online PC. A friend installed my offline Ubuntu laptop, I'm not familiar with Ubuntu and don't want to troubleshoot through the upgrade procedure right now.
It's the Windows7 64 bit version I'm looking for, for my online PC.
You are seriously better off updating the offline signer than trying to get 0.91 online. That will be painful, trust me. I'm not it will even manage to at this point. If you insist on running 0.91, you will most likely have to build it from source, in which case you are better off doing this on some Debian/Ubuntu distro as it is fairly easy to build on those.