Add-in file XRealStats.xlam is blocked by default for some reason - solution found

The add-in required for this course is blocked by default and excel throws multiple errors when you try to load it using the add-in manager.  The solution is to unblock the file in windows manager before trying to access it using excel. Right-click on the file and click properties. On the general tab there should be an 'unblock' option at the bottom. It worked fine for me after this. The Add-ins tab also became visible when it had loaded.

Solution taken from...  https://answers.microsoft.com/en-us/msoffice/forum/all/add-ins-tab-not-showing-in-ribbon-in-excel-2016/70858ed7-8379-47eb-abdf-ee42fa070ef4