The output of the DateTimeStamper is already an attribute. You do need to make sure you have that attribute defined on your output feature type though.

Thanks for your quick answer, indeed it's an attribute , called "_timestamp" , i need to replace "_timestamp" with the date of today

You can do this in an AttributeManager.

The attribute will not be exposed. To expose the attribute, you will have to enter it's actual name in an AttributeExposer.

Thanks for your answer geomancer

After using your tips , i obtain this screenshot, is it normal ?

In the AttributeExposer, you have to enter 20221121 (or any other attribute name you want to expose). Entering @Value(_timestamp) will not work.