Your public page lives at:
Extra pages use a slug: https://yourname.dimensions.fm/your-page
Set or change your username
Open your avatar menu → Settings → Domain.
Edit the username next to .dimensions.fm.
Tap Save username. You should see Username saved. If that toast doesn't show, it did not save.
Usernames are lowercase letters, numbers, and hyphens only. Names like www, app, start, links, api, mail, cdn, ftp, staging, preview, link, auth are reserved.
If it's taken you'll see This username is already taken. If it's reserved: That username is reserved.
Custom domains
A custom domain (yourname.com → your Dimensions page) is a 301 forward, not masking. It's included with Pro Max, older Pro plans, and Label/Team. New Pro does not include it.
Set it under Settings → Domain → Custom domain. You'll add a URL forward at your registrar (GoDaddy, Namecheap, Cloudflare, etc.).