Mac mini activation error: 'server not found' after erase

I wanted to completely factory reset my Mac mini so I went to general > transfer or reset mac> and clicked erase all content.

After that the Mac started up again, showing the Activate Mac screen, but when I tried to start the process by connecting to the WiFi it just says “A server with the specified host name could not be found.”

I am gifting it and want to make sure that all my data is gone and it’ll work fine. What do I do?