Problem with adding domain for email service

Problem with adding domain for email service

Hi,
We want to add this domain advancedlanguageinstitute.com , but we have similar problem like this person:
https://help.zoho.com/portal/en/community/topic/the-data-you-have-entered-already-exists-when-trying-to-create-contac-mydomain-com

But problem is not secondary email wihich we deleted.
This is a error message:
The data you have entered already exists