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

According to the docs, Table.FuzzyGroup can be passed up to four parameters: table, key, aggregatedColumns, and an optional options record.

You're passing it five parameters.

Table.FuzzyGroup(
    #"Changed Type",    // #1
    {"Name Keyword"},   // #2
    {
        {"Count Name Keyword", each Table.RowCount(Table.Distinct(_)),Int64.Type}
    },                  // #3
    [
        IgnoreCase = true,
        IgnoreSpace = true,
        Threshold = 0.42
    ],                  // #4
    {
        "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]
    }                   // #5
)

It looks like you may have started with a fuzzy group that just computed a count, but then added a new aggregated column ("Group By Name Keyword") at the end of the parameters, instead of adding it to the existing list of aggregated columns.