Hi mariannakat,
You started from a good resource. If you see the Restore screen on your iPhone, iPad, or iPod touch
For help with getting your iPhone updated and connected to your Mac, view the requirements and steps below found in the guide here: Connect iPhone and your computer with a cable - Apple Support
- "Make sure you have one of the following:
- Mac with a USB port and OS X 10.9 or later
- PC with a USB port and Windows 7 or later
2.Connect iPhone to your computer using the charging cable for your iPhone. If the cable isn’t compatible with the port on your computer, do one of the following:
- If your iPhone came with a Lightning to USB Cable and your computer has a USB-C port, connect the USB end of the cable to a USB-C to USB Adapter (sold separately), or use a USB-C to Lightning Cable (sold separately).
- If your iPhone came with a USB-C to Lightning Cable and your computer has a USB port, use a Lightning to USB Cable (sold separately)."
Typically, you can connect your iPhone to your Mac using the same cable you use to charge your iPhone. If needed, you can view both cable types here as well: Charging cable for iPhone
Once connected test the steps in the section "Put your device in recovery mode and set it up again" here: If you can't update or restore your iPhone or iPod touch
If the issue continues reach out to Apple Support to assist.
Contact - Official Apple Support
Contact Apple for support and service - Apple Support
Best.