new user alway showed as pending status

new user alway showed as pending status

hello,

my colleague "m.oleksandr @ sungrow-emea.com" is always pending and can't join in Zoho. Received invatation mails many times, but can not login in with the link in the invatation mail. It said"an account already exists with this email adress in the eu DC. Please contact support..."  He can login Zoho One with his email adress and password, but the account is still not activiated.
need your help! many thanks!

Fang