After I install or manually load the Add-in, no menu or ribbon appears

Some relatively unusual settings can impact loading add-ins, as they disable the ability to run them.  To check these settings, follow these steps:

Excel 2003: Choose Tools | Macro | Security | Trusted Publishers and then make sure the two available check-boxes are checked.

Excel 2007: To see this setting, go to Excel Options from the Office button in the upper-left corner of Excel, then Trust Center, Trust Center Settings, Add-ins, then make sure all three of the options there are unchecked.   Pick both Com addins and Excel addins from the pick list at the bottom of the windows, and then make sure none are loaded Except BRC Addins.  Then restart Excel.

Excel 2010 – 2016:  Use steps similar to Excel 2007  to find the Trust Center Settings.