By allowing Streak access to your cookies, you are granting Streak the ability to remember that you have already logged into your account. With third-party cookies enabled, Streak will not have to ask for permission each time you log into Gmail.
If you use any browser extensions that block cookies from being set such as: ad blockers, Privacy Badger, and/or Ghostery, then you will likely not be able to load Streak.
If your browser doesn't allow cookies to be set or clears out your cookies after closing your browsing session, too, then you will have to re-authorize and login to the Streak extension every time you load Gmail.
Enabling cookies in Safari
Click Safari in the upper left-hand side of your screen and select Preferences from the dropdown menu.
In the new window, open the Privacy tab.
Please make sure "Prevent cross-site tracking" and "Block all cookies" are disabled.
Refresh your Gmail after disabling.
Enabling cookies in Chrome
Navigate to your settings (chrome://settings) from the three-dot menu in the top-right corner.
Scroll down until you reach "Privacy Settings" and select "Content settings" from the list.
Click into Cookies.
Please make sure "Allow sites to save and read cookie data (recommended)" is enabled.
Please make sure "Block third-party cookies" is disabled.