When your supporter starts filling out their street address, the form will automatically start to suggest an address to make entering that information that much faster and easier for your supporters. When you select an address, it will populate the Address, City, State, and Zip.
This feature is automatically enabled on activities created in or after February 2020. If you have an activity created before this time, then it may be disabled, so the function of the form is as you knew it when you created it. You can still enable this feature on previously created activities, though as outlined below.
Go into the activity you wish to enable the Address Lookup feature.
Go to the Online Form category in the right and open the Contact Information section of the appropriate form.
Click on the Edit icon for the Street Address.
Enable the switch by Assist filling address info.
Click Save.
Your form should now automatically fill the address as you type it.