How to get a URL for your Google MyBusiness page:
Do a search for your business in Google Maps at https://maps.google.com
Click the "share" icon
Copy the URL (change to a short URL to make it more manageable for emails etc)
You can then use to update your Google Business icon on your website by updating the social media icon setting in site builder.
And you can add the link to your booking engine guest emails as well.