Expression.Error: 5 arguments were passed to a function which expects between 3 and 4. Details:

I'm not sure exactly what you're trying to do, but I suspect you need to move the "Group By Name Keyword" definition into the list of aggregated columns.

Table.FuzzyGroup(
    #"Changed Type",
    {"Name Keyword"},
    {
        {
            "Count Name Keyword",
            each Table.RowCount(Table.Distinct(_)),
            Int64.Type
        },
        {
            "Group By Name Keyword ",
            each _,
            type table [Name Keyword=nullable text, RecordTypeId=nullable text, BillingCountry=nullable text, ShippingCountry=nullable text, OwnerId=nullable text, Business_Unit__c=nullable text, National_Account__c=any, Status__c=nullable text, ADM_Geography__c=nullable text, Account_Customer_IDT__c=nullable number, Classification__c=nullable text, Entity_Description__c=any, Source_System__c=nullable text, Market_Segment__c=nullable text, Region__c=nullable text, SAP_ECC_Id__c=nullable number, Record Type.Name=nullable text]
        }
    },
    [
        IgnoreCase = true,
        IgnoreSpace = true,
        Threshold = 0.42
    ]
)