Instead of adding the printer to the existing network, you may attempt to print via Wi-Fi Direct.
In case this does not work as well and you refuse to use HP Smart, it's on you to bring the right drivers and install them manually. There are 8020e drivers for offline usage on HP's webpage (please double check it's the right make and model, at the top you see the selected printer & target OS).
On the webpage you want to:
- close the "recommended" solution HP Smart,
- open Installation Software and Full/Basic Driver-Supports print and scan functionality only,
- then snatch the HP OfficeJet Pro 8020 All-in-One EasyStart Printer Setup Software – Offline Use Only.
It's probably best you load these onto a USB stick and bring them to your neighbors. Maybe guide them through the installation as well. After the drivers are installed, you should have no problems adding the driver in the native Windows printer selection. Both printing via the local network as well as WiFi-Direct should work flawlessly now.