Cognizant — Not able to sign in one cognizant

Hi,
I got the offer letter from the cognizant on 24 may, 2023. I'm unable to sign in the onecognizant portal. And also I cannot submit the acceptance of offer letter and background verification too. I also send the issue mail at may 25, 2023 to [protected]@cognizant.com. But till now there is no response. Repeatedly it shows like follow:

Sorry, but we’re having trouble with signing you in.

AADSTS90072: User account '[protected]@gmail.com' from identity provider 'live.com' does not exist in tenant 'Cognizant' and cannot access the application 'https://onecognizantexternal.cognizant.com'(ENT_onecognizantexternal_SAML_PROD) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account
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Request Id: beca6689-0ede-4eb5-b687-8016ca279c00
Correlation Id: 623a5d[protected]f-9104-6ad67f6af9c2
Timestamp:[protected]T12:58:57Z
Message: AADSTS90072: User account '[protected]@gmail.com' from identity provider 'live.com' does not exist in tenant 'Cognizant' and cannot access the application 'https://onecognizantexternal.cognizant.com'(ENT_onecognizantexternal_SAML_PROD) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account
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Request Id: beca6689-0ede-4eb5-b687-8016ca279c00
Correlation Id: 623a5d[protected]f-9104-6ad67f6af9c2
Timestamp:[protected]T12:58:57Z
Message: AADSTS90072: User account '[protected]@gmail.com' from identity provider 'live.com' does not exist in tenant 'Cognizant' and cannot access the application 'https://onecognizantexternal.cognizant.com'(ENT_onecognizantexternal_SAML_PROD) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.

Please give the resolution.