Just set up new account and cannot get the sidebar to pop up.
Thanks for letting us know. Google has some issues with their add-ons at the moment which is affecting our Google Sheets services as well. Terribly sorry for this.
You can read more and receive updates at ***Service outage (Supermetrics for Google Sheets) 06-07-2018***
Hi. This issue is now fixed. If you refresh your browser tab with Google Sheets, Supermetrics should open up normally from the add-on menu. This time it will ask you for a permission and opens it up in a new window but it will happen only once.