Some forms use the so-called "Google Maps" function in address fields to quickly find addresses.
While you are entering a street name, suggestions are displayed that you can transfer directly to the address form with a click of the mouse.
Since the house number is not yet known at this point in time, this function cannot always provide the correct postcode. This is because many streets extend over different postcode areas.
However, to take over the postcode at the same time, proceed as follows:
First enter the house number in the field for the street, followed immediately by the name of the street.
When the correct suggestion is displayed, select it with a mouse click.
The "Google Maps" function can then determine the correct postcode based on the house number, even for longer streets, and the postcode is automatically entered in the form.
With this little trick, the entire address can be completed directly.