Hi Colleen,
Steve Flowers talks about this issue in his post in this discussion:
https://community.articulate.com/discussions/articulate-storyline/how-do-you-perform-functionality-testing-for-your-elearning-on-multiple-browsers-osHe mentions the free virtual machines you can download from Microsoft, that will test various versions of IE:
https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/linux/There's also CrossBrowserTesting.com (not free), that says it has "Access to over 750+ browsers across 55 different operating systems and mobile devices" for testing purposes.
I generally just test on what I have, and that's it. The latest versions of Chrome, Firefox, & IE, and then Safari and an Android tablet. Even that seems ridiculous to me! Everything should just work on everything, right? :)