Total Sum by Column (Matrix)

if source is your tab,

then open an empty query and paste the following code ovewriting all.

let

Start_End = (SD, ED, optional Culture as nullable text) as table => 
  let
    StartDate= Date.FromText(SD,[Format="dddd d MMMM yyyy", Culture=Culture]),
    EndDate= Date.FromText(ED,[Format="dddd d MMMM yyyy", Culture=Culture]),
    DayCount = Duration.Days(Duration.From(EndDate - StartDate))+1, 
    Source = List.Dates(StartDate,DayCount,#duration(1,0,0,0)), 
    TableFromList = Table.FromList(Source, Splitter.SplitByNothing()),    
    ChangedType = Table.TransformColumnTypes(TableFromList,{{"Column1", type date}}), 
    RenamedColumns = Table.RenameColumns(ChangedType,{{"Column1", "Date"}}),
    res= Table.AddColumn(RenamedColumns, "gant", each 1)
  in 
    res,

     #"Grouped Rows" = Table.Group(source, {"Category", "Name", "Task Type", "Assigned To"}, {"from to", each Start_End([Start Date]{0},[Expected End Date]{0},"it-IT")}),
    #"Expanded from to" = Table.ExpandTableColumn(#"Grouped Rows", "from to", {"Date", "gant"}, {"Date", "gant"}),
    #"Pivoted Column" = Table.Pivot(Table.TransformColumnTypes(#"Expanded from to", {{"Date", type text}}, "it-IT"), List.Distinct(Table.TransformColumnTypes(#"Expanded from to", {{"Date", type text}}, "it-IT")[Date]), "Date", "gant", List.Sum),
    #"Grouped Rows1" = Table.Group(#"Expanded from to", {"Date"}, {{"total", each List.Sum([gant]), type number}}),
    #"Transposed Table" = Table.Transpose(#"Grouped Rows1"),
     GranTotal = Table.PromoteHeaders(#"Transposed Table", [PromoteAllScalars=true])
      in 
      Table.Combine({#"Pivoted Column",GranTotal})