How to open .bin file?

You can't just convert a .rar file and expect the output file to be useful. RAR is a compressed format, such as ZIP, and needs to be extracted with a tool that can expend the .rar format.

The free Stuffit Expander, available on the App Store, will expand a RAR archive.

.bin just says it is a binary file. Try using a free utility such as The Unarchiver to see if you can get something more sensible out of the rar file. Note that rar is a Windows compression format so you may be going into this with a Windows biased file offering to start with.

One can drop into the Terminal, and if for instance that .bin file were in Downloads:

$ comment: do not type the '$' sign

$ cd ~/Downloads

$ file -I ./blah.bin

I am most accustomed to seeing non-Apple router firmware files distributed in the .bin final format — because they are binary files.

That’s s firmwre update, not a manual

Without knowing what to do with the extracted .bin file, yes, you're stuck for the time being.

Could you provide a link to the page where this manual is? I'd like to see what's going on. No promises I'll get any further, but I'm curious.

Or, since a .bin is yet another compression scheme, that itself likely needs to be opened. Here's one set of instructions that may work.

https://smallbusiness.chron.com/extract-macintosh-bin-files-45530.html

Ah. When you said you converted it, I had to assume you used some sort of compression utility to simply rewrite the .rar file to a different format.

So, a .bin file is what came out of it. I doubt a new download will change anything since the file that was extracted is exactly what was supposed to come out of the .rar archive. Why a manual would extract as a .bin file is anyone's guess. Why not a PDF?

That's what I thought. But apparently, the people who built their site were more interested in looks than usefulness.

http://auto-vox.com/

There's only one spot to download anything for these two items (whatever they are):

And even for those, you have to supply a password.

Hard to believe they do not provide the manual in the standard pdf format someplace. What is the exact name of the product?