Hi, I’m a newbie that had the same issue. If you are on facebook, there is a group called WPTuts that is awesome, and that’s where I got “unstuck” after two days of troubleshooting with the same issue. Basically there are two ways to insert the information. When you click on the dynamic tag, don’t go down to “ACF Fields” but rather go to “Post Custom Field” and type in the key name of the field manually. Here’s a video that was sent to me that helped me out https://cloud.2urn.com/lluJ87kQ?fbclid=IwAR0aBj2jO39GCddbnSt_FboBx9iEwxcKYWh_dzyuwRSj3JBHTP1bpGyVoY0
I hope that helps!