Even if Access is too smart to actually use the runtime engine when you have Access retail installed, you still should be able to find the download file. The actual file name is AccessRuntime.exe.
You can change your Windows Explorer settings to show extensions (I can't figure out how people can work with extensions hidden) and show hidden system files. The .exe you downloaded isn't a hidden system file so I'm not sure how that would apply.
If you know the default download location, you should be able to find the file.
Once you find it, DO NOT install it on your computer. It will only cause confusion. Only install it on computers that do not have Access at all or that have older versions of Access.
BTW - I never let users have multiple Access versions installed if I can help it. It is just too confusing to always get that pesky .....installing...... message as Access fights for control over the registry with whatever version was previously installed. For development, I have one PC with multiple versions for cross testing but I am careful as I switch and so haven't run into problems. The A2010 runtime can run older versions so if the users don't actually need full Access, just get rid of all old versions.