To find your Apple Music URL, follow these instructions:
From the Apple Music website
Go to the Apple Music website
Type your artist name in the search box in the top left, then press Enter
Check if your artist photo appears under 'Top Results': if it does, click on it, otherwise look for it in the 'Artists' section underneath
Once you're on your Apple Music artist page, go to the URL field of your browser and copy the link, which should have a format similar to this:
https://music.apple.com/artist/{artist-name}/{apple-music-id}
From the Apple Music app
Open the Apple Music app on your phone or computer
Go to your artist page
Click on the three-dot options menu in the right
Then select 'Share Artist': this will pull your Apple Music artist page URL
Once you have your Apple Music artist page URL from either the Apple Music website or the app, you can open Bandsintown for Artists and go to your artist's Profile » Links page where you can now paste this URL in the Apple Music field: