Sum items between dates for each date

Nevermind, I was able to transform the table in the Query Editor

Here's the code

let
    Source = Excel.Workbook(File.Contents("C:\Users\e.ordaz.maurera\OneDrive - Accenture\Analytics + AI\IC\Mock.xlsx"), null, true),
    Table1_Table = Source{[Item="Table1",Kind="Table"]}[Data],
    #"Changed Type" = Table.TransformColumnTypes(Table1_Table,{{"Client", type text}, {"DateStart", type date}, {"DateEnd", type date}, {"Items", Int64.Type}}),
    #"Inserted Date Subtraction" = Table.AddColumn(#"Changed Type", "Subtraction", each Duration.Days([DateEnd]-[DateStart])),
    #"Added Custom" = Table.AddColumn(#"Inserted Date Subtraction", "Date", each List.Dates([DateStart],[Subtraction],#duration(1,0,0,0))),
    #"Expanded List" = Table.ExpandListColumn(#"Added Custom", "Date"),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded List",{"DateStart", "DateEnd", "Subtraction"}),
    #"Grouped Rows" = Table.Group(#"Removed Columns", {"Client", "Date"}, {{"ItemsSum", each List.Sum([Items]), type number}}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Grouped Rows",{{"Date", type date}})
in
    #"Changed Type1"

Thanks to this post on http://radacad.com/dates-between-merge-join-in-power-query