With Tolt, your affiliate portal can have a custom domain, i.e. affiliates.domain.com instead of a subdomain.
The setup for this is pretty straightforward. Although you need to have access to your DNS provider(i.e. Cloudflare) or register(Namecheap, Godaddy etc...).
You need to create a CNAME record of your desired domain that will point to domains.tolt.io.
First, add your domain in Program Settings -> Affiliate Portal:
Then inside your registrar create a CNAME record with the domain you add inside Tolt.
For this tutorial, I'll be using Cloudflare:
Afterward, go back to Tolt and click Verify.
Note that the domain might take a few hours to be verified!
If the status says VERIFIED, then your affiliates can access your portal with the new domain!