If you are not able to access the CRM Server, there is no way you can add a new AD user, the error message you are getting above, is indicating an issue with the user. If you query
USE ORG_MSCRM
select domainName from systemuserbase where IsDisabled = 0
and share the results with me i will look into that. another thing that i request you to verify here is the the status of the organization . You may run the query
Use MSCRMONFIG
select state from organization