I'm sure you know that CTR is clicks divided by impressions. But are you sure how to calculate it if you have several rows in the table?
This video is more theoretical but the theory is important to get the correct numbers in your dashboard.
Google Sheets that I use in this video - https://docs.google.com/spreadsheets/...
Articles about Looker Studio and Google Sheets - / givannikova
https://gaillereports.com/blog/
Report prepared by Gaille Reports - https://gaillereports.com/
Telegram channel - Gaille Reports: https://t.me/gaillereports