Using Excel for Macintosh? Choose Analytic Solver Cloud.
Click here for info on Microsoft's Office 365 subscriptions. For students, there is a free online (browser) version, and a low-cost desktop version.
Analytic Solver Cloud requires a very recent version of Excel. Excel Online in a browser is always up-to-date. On a Mac, you'll need Version 16.25 or later (System menu, Excel - About Microsoft Excel). On Windows, you'll need Version 1904 or later (File - Account - About Excel).
An Office 365 subscription will install the most recent version. If you cannot do this, choose Analytic Solver Desktop. It will work with Excel 2010, 2013, 2016 or 2019 for Windows (only). If you have a Mac, consider an Office 365 subscription, or see this page.