I have Zoho One, and have integrated Zoho Books with the CRM. Everything works fine for me (I am the Super Administrator). 

Security for all modules is set to Read/Write/Delete, and Zoho Finance is turned on in the security settings. 

I have other users with Manager > Standard access. When they create an Estimate through the CRM link and then try to email it, they get the error message "You do not have sufficient permissions to perform this operation. Contact your administrator."

I changed the Role for one of the users to Administrator. She can now bring up the screen to email it, but the sender is my email address, and she cannot change it to her email address. 

As a workaround, she can go into Zoho Books, open the estimate there and email it and it works fine. So it appears to be a security setting in CRM, but I can't figure out how to fix it.

Any help is greatly appreciated!