Hey there,
I hope you are well today and thank you for your question.
You can refer to Laranz first solution on this post:
https://colorlibsupport.com/t/single-scrolling-page-navigation-menu/
Each widget will have its own unique IDs you’ll have to use these IDs for the button URL.
You can use the google inspect tools to find widget ids. They look like this: #shapely_home_contact-2
Your website requires me to sign in so I cannot see beyond that to assist you.
Best regards,
Support.