Recently, I ran into Apple Maps and how it works. I have found we need to create a MapKit JS key to work with Apple Maps.
IMPORTANT: To follow this guide you should have Apple Developer Membership
Here is a visual step by step guide:
Open https://developer.apple.com/account

Click on Certificates, Identifiers & Profiles

Click + to the right of Identifiers

Now we need to register a new identifier and choose Maps IDs as a value. Then click Continue

Enter inputs and click Continue

Make sure all values are okay. Click Register

We successfully registered a new identifier. We can filter identifiers by clicking on the magnifier icon

Now we are going to create a key. Press Keys, then Create a key button

Enter the name for your key and enable MapKit JS. Then click Configure

Search for a newly-created identifier and select it

Click Save

Press Continue

Press Register

Now we need to download key
IMPORTANT: You can download the key just once!
If you are ready, press Download

Download prompt will appear in the browser

Now you can use this key in your projects.
To check key details, open Keys

Click on the key and view details

That’s a visual guide through obtaining MapKit JS private key. You can use it for Apple Maps in your WEB-applications. You can see an examples to understand what you can build.