KeyAGS Excel extension not available in excel despite installing correctly.

We currently run the latest version of the KeyAGS Excel Add-In (V4.4.4.83) on our PCs and everyone's is working fine with this version and Excel. We have a new starter whos PC has the same version of Excel and the KeyAGS Add-In, however there is no option to add it as an add-in (under options> Add-ins in excel) and the ribbon along the top with the KeyAGS tab hasn't automatically appeared.  There were no issues with the installation and we have already tried uninstalling and reinstalling just in case.

Any help would be great, hanks in advance.