Hey there, this is happening because the DNS zone you’re trying to use already exists on Netlify under a different account-- probably your previous web developer’s account.
The quickest way to get this resolved is for you to contact that person directly and ask them to remove the DNS zone from their account here: https://app.netlify.com/teams/TEAM-NAME/dns/oatmealandcompany.com Once that’s done, you should instantly be able to add the custom domain to your account.
Your previous web developer could also initiate a DNS zone transfer via this form https://www.netlify.com/support/ using the email address associated with their Netlify account. They would just select “Site/DNS zone transfer” from the dropdown menu there, and we could transfer it over to you.
Or, if those are not possible for whatever reason, please verify domain ownership and let us know when that’s done. If the verification is successful we can delete the DNS zone from the other account so you can use it on yours.
Sorry to hear about your downtime, and hopefully we can get you on your way quickly!