Login to your Gemini account and select API Settings from My Account dropdown list on top right.
Click on ''Create A New Account API Key'' button and input the code sent to you by SMS.
You will see a screen like below with your API and Secret Keys.
Name your API with any name you'd like (ex. CoinStats Gemini), and make sure to mark access to Auditor under API Key Settings menu.
Please make sure to copy/paste your Secret Key to a safe place, as it will only be displayed at the time it is created. If you lose this key, you will need to delete your API and set up a new one.
Now go to CoinStats app Portfolio tab, swipe far to the right and click Connect Exchange.
Select Gemini from the list and paste your API Key and API Secret.
After clicking Submit you will see your Gemini portfolio synced with the CoinStats app.
Refer to support in case of further questions. Hope you'll enjoy!