Who is your Internet provider (ISP)?
What type of broadband are you on?
What modem do you have? Make and model please.
If you plug your modem directly to the MacBook by ethernet what IP configuration do you get?
Please show us the results but blot out any public IP.. at least some digits.. I would like to see the first two e.g. 200.100.x.x
If your internet happens to be a building type.. and you have no modem.. just a direct ethernet in the wall. It is not uncommon for it to hand out 10.x.x.x addresses which will fail immediately. That is this range used by the Airport lan.. ie 10.0.1.1 and it needs to be moved first.
I’ve tried plugging it in to the MacBook via Ethernet. Airport Utility recognizes it but fails every time.
Yeah.. they can be stubborn little wretches.
I am surprised the iOS version Airport Utility failed as that is generally better.
So here is how to do it.. MANUALLY.
Please follow step by step and tell me exactly the point where it fails.
1. Humour me.. do another factory reset.. We want to start with blank slate.
2. Plug into the MacBook by ethernet. No other connections at this stage.
3. Open airport utility and go to Other Wireless Devices (1) and change over to ethernet.
In the airport utility now ethernet is under Other Wi-Fi Devices.. which makes no sense at all. Ethernet will only show up when it is connected and working.

4. Click on File and Configure Other.

5. Type in the IP address.. always 10.0.1.1 after a reset. No password needed yet.

6. Now you can see all the parts of the setup.. you will go to each tab to do the setup.

7. First is Base Station.. and change the name .. short, no spaces and pure alphanumerics.
This is rather old.. but name it say.. AEgen6 for example.
Use a password that follows exactly the same rules.. but can be longer.. 8-20 characters but more if you like.
Make sure setup over WAN is off.

8. Internet tab will be DHCP for most people with nothing else..

9. Wireless tab

10. Then network.. pick what you want yourself.. you are now in control.
For most people they will set DHCP and NAT if you have a pure modem or Off (Bridge Mode) if you already have a router.

5. Once you finish making changes.. use Update to configure them to the Airport.. and wait for it to reboot..
If all is good it will come up on the main utility.

If this still has errors just click the Airport icon and go back into the setup and fix anything there.
Any step fails tell me which one..
Once you complete the configuration.. now plug in the WAN connection. Remember wan is the one next to the bottom on the AC airports.