Update author of a created entity by anonymous

Ok, then I managed to succeed.
You just have to update the field uid of the created entity.
I am sorry for my stupid question. I've spent a lot of time for this result.

Yes, finding the field names for all entity types anywhere can be tricky. A good place is the "Manage form display" page for the entity and bundle you're looking for, e.g. /admin/structure/types/manage/article/form-display for article nodes. That shows you the machine name of all the available fields.