Hello, having the exact same issue as OP. The link for the SafeA9LHInstaller on the guide was dead so I just went to the github manually and downloaded it. There was no arm11.bin file in the zip and as a noob I didn't realize it. Will try to new link munchy_cool has posted.
I didn't know they made an MSU cart for the Genesis.... I knew about the SNES one and the library for that is rather large but the Genesis one has very few games