how to download interent explorer on a mac book pro

No, Microsoft does not make an OS X version of Explorer. The only way to use it is to use boot camp or VM Ware and the like to install Windows on a separate partition of the Mac.

Safari does have an Explorer emulator mode though. Open Safari, then Devlop > User Agent and select an Explorer version you wish to emulate. It only goes up to Explorer 10 right now though but it helps me.

You can run windows on your Mac either natively using Apple's BootCamp or as a virtual machine on top of OSX using an app like the free VirtualBox or paid Parallels. Yo have to purchase the Windows software

There is only one reason a site would specifically only work with IE, and that's a poorly written site that still depends on ActiveX. Known to be one of the worst ideas MS ever came up with (Yeah, great idea boss! Let's let remote web sites run software directly on other user's computers without even giving them a choice!). It was such a bad idea that MS themselves FINALLY admitted it and took it out of IE in Windows 10.

If the site doesn't require ActiveX to work, then it's an even more poorly written site that uses the idiotic HTML code to detect what type of browser you're using, and won't work if it isn't the one they want, even though there's nothing about the site that won't work in any other browser.