To Add a Picklist to an Item's Property Definition

Open the Item Types dialog (Drawing > Content > Item Types > Item Types Dialog Launcher).

Select the desired Item type property definition.

In the Properties pane on the right, select Type as Text then select the desired Picklist name from the drop-down menu in Picklist row.

Select the desired Picklist name from the drop-down menu in the Picklist row.

The Picklist gets associated with the property definition.