Running IE on a Mac used to involve buying a copy of Parallels or VirtualPC, then getting a Windows installer and a license activation code. But thanks to some visionaries over at Microsoft and Oracle, the whole process is fairly straightforward and best of all, free.
First, install the latest VirtualBox host. This is the software that makes your look like a standard PC computer.
Next, head over to Microsoft and download a free virtual machine with the version of Windows and IE that you need. If you're not sure, I recommend the latest stable version of Windows (currently Microsoft Edge on Windows 10 stable); It includes both Internet Explorer and Microsoft Edge. Make sure you unzip using The Unarchiver.
I just use the defaults when creating the new virtual machine. I don't need anything high-powered here; I'm just using it for the browser. Start it up, and first thing click the Windows logo (lower-left), Settings (gear icon), Update and Security, Check for Updates. Apply all updates, restarting if necessary. Once your are completely up to date, click Take Snapshot in the Machine menu.
When the license evaluation period is over, you can reset the machine to this snapshot by clicking Snapshots in the upper-right corner of the VirtualBox Manager window. Or you can just keep the source ova file around, delete the VM and create a new one from the ova.