In the guides, Facebook says
Add both your Facebook App ID and Account Kit Client Token to your Info.plist file as strings. Make sure you have enabled Account Kit in the App Dashboard. You'll find the Account Kit client token in the Account Kit section of the App Dashboard
However I really have no idea where to enable it. Could anyone please help with a visual guide? I have been trying to find it for 2 hours.
You can find your Facebook App ID and Account Kit access token if you go to your app in the App Dashboard.
The app dashboard is located at: https://developers.facebook.com/apps/INSERT_YOUR_APP_ID/dashboard/
To add Account Kit click "+Add Product" on the left. The Account Kit page in settings will display your client token, and the main dashboard page will display the Facebook App Id.