Got the error message about DKIM not connected to my domain. I've added the TXT field to my DNS settings in Squarespace, but Zoho is not verifying it. I've also tried testing it on this third party site:
It gives me the following error message when checking a 'published DKIM Core Key':
No TXT record for zoho._domainkey.gnashswim.com
A public-key (p=) is required