An Excel Web Add-In can set to be automatically installed when opening a template file.
Does this work in any environment?
The AutoInstall feature is available under the folllowing preconditions:
- "Newer" Excel Version:
Excel for Windows Desktop. Build 16.0.8121.1000+
Excel for Mac. Build 15.34.17051500+
Excel Online
How to activate the AutoInstall feature of the data1.io Web Add-In in a Template File
The Excel Web Add-In at first must be saved with the Template File (see here). Then close and rename the template file from "*.xlsx" to "*.zip". Navigate to the file "taskpanes.xml" and create a copy somewhere outside of the zip-file. Then change the setting "Visibility=0" to "Visibility=1" (e.g. with a simple text editor) and copy the modified file back into the zip-file and replace the existing taskpanes.xml:
If a user opens the template file without already having installed the Excel Web Add-In then she or he gets displayed this dialog with the Button "Trust this add-in". Pressing this button will install ("add") the Web Add-In on this device of the user:
Ressources
https://dev.office.com/docs/add-ins/design/automatically-open-a-task-pane-with-a-document