Hello @Santosh V ,
The error comes because when you are installing SharePoint Server 2019, you need a domain account. It should be an active directory domain account.
Please run the below New-SPConfigurationDatabase cmdlet as an admin
New-SPConfigurationDatabase -DatabaseName SharePoint_ConfigDB -DatabaseServer [ServerName] -AdministrationContentDatabaseName SharePoint_ContentDB -Passphrase (ConvertTo-SecureString [password] -AsPlaintext -Force) -FarmCredentials (Get-Credential) -localserverrole SingleServerFarm
Thanks,
Echo Du
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