Most common issues:
1. Script is not embedded.
If you are using Shopify please follow the install instructions here. If you are installing directly for via Google tag manager please use the install instructions found under the profile menu in the dashboard.
2. Survey is not published.
Ensure you've gone to step 4 of the survey editor and published your survey. In draft mode it will not be visible.
3. Survey has been answered once.
By default, the survey will only show once per user. After testing it once it will not show again. Use Chrome's incognito mode or Safaris Private mode to get it to show again. You can change this behaviour under the 'Delivery' page of the survey editor under 'Site widget -> Widget recurrence'
4. Targeting is incorrect
Under Delivery -> Site widget you can choose which pages to show the survey on and which users to show it too. Ensure targeting matches the page you are testing on.