@Hundasuupa Does the add-in work with older versions Excel? if so, how far back is it supported?
Is it or would it be possible to download the add-in as an Excel Add-in file (.xlam)? - so that compatibility with older versions of excel can be explored - specifically I’m wondering if it would work with Excel 2013 which does support Add-ins but only if you have the file locally on your pc (not via shop-style management which is found in Excel 365).
nope only office 365, which is a shame 
Retail Excel is not supported, only web excel and 365 subscription desktop clients.
The add-ins from the shop, and the Eve addin aren’t COM/.dll’s like in previous excel versions (AFAIK, I’m not used to having had to use add-ins in excel before this project)
Instead they are run via Javascript, using the office-js library, so it’s essentially a website that can hook into Excel.
There were some issues with properly detecting the compatibility with the rich data features used by the add-in, and we’ve just got the confirmation about compatibility with retail Excel, so even 2019/2021 excel sadly can’t use the add-in either.