The following example will populate some of the form's fields with some data from a Craft Entry.
In order to view this page live, you'll need to make some adjustments to this template or on your test from:
freeformCraftEntryData
or adjust the form handle name inside this template to match your test form.productId
.productTitle
.productUrl
.freeform-test
and includes the following Craft fields at minimum, or adjust the overrides inside this template: