Hi @Rob Love ,
What version of Excel did you use?
I suggest you check if your Excel version is supported by this add-in:
*- Excel 2016 or later on Windows
- Excel on Mac (Microsoft 365)
- Excel on Windows (Microsoft 365)
- Excel on the web
*
I also suggest you refer to this support article and check if you can get any help from it:
https://learn.microsoft.com/en-us/office365/troubleshoot/installation/cannot-install-office-add-in
Just checking in to see if the information was helpful. Please let us know if you would like further assistance.
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