Where we have to maintain assets credentials in config file. But Not in the Assets config.
You pass the values in the Settings sheet in the config file.
App_Credential → Asset name (Credential Datatype)
As explained key @Gokul001 you can store the Credential assets in the Settings sheet of config in the form of key value pair.
Later on you can use the Key out out of that key-value pair in the Get Credential activity like
Config(“Key”).ToString and you will get the username and password as a output of Get Credential activity.