Wrote a guide
Launched Polywork profile
Setup custom domain for your Polywork profile (non-www + www) with Cloudflare Page rules

I was running into an SSL error when I used the custom DNS target for both non-www and www DNS records, by using page rules you can redirect users to just the non-www domain where the Polywork domain setting is linked to.

1. In your Polywork settings enter your non-www domain name and get your custom DNS target.

2. At Cloudflare create 2 CNAME DNS rules:
    1. Name: @ (this will later automatically be replaced by your domain)
        Content: your custom DNS target
    2. Name: www
        Content: @

3. Go to Rules and create a new Page Rule:
    Url matches: www.<domain name>/*
    Setting: Forwarding URL
    Status code: 301
    Destination URL: https://<domain name>/$1

Done! 🚀