Zoho Books Quote - Client cannot accept quote

Zoho Books Quote - Client cannot accept quote

We are using the Zoho One plan and some of our clients have reported that they cannot accept the quote when we select their email at the bottom to send the quote to.

When trying to accept, the quote prompts a message saying "You are not allowed to accept this quote. Please contact your vendor for assistance". 

The "accept quote using payment link" has been checked under settings, so I'm stumped at what we are missing here.