Not released yet.
This app is built and working, but it is not on the Atlassian Marketplace. It needs Google's OAuth verification before anyone outside our own site can connect a spreadsheet to it, and that queue is measured in weeks.
There is nothing to install and nothing to buy. This page exists so that the links inside the app lead somewhere honest rather than nowhere.
If you want to know when it is available, email [email protected] and we will tell you once — no list, no follow-ups.