How to transpose column value into header

NewStep=Table.Combine(Table.Group(YourTable,{"Order No.","Material"},{"n",each #table({"Order No.","Material"}&List.Transform({1..Table.RowCount(_)},each "Deliver no. "&Text.From(_)),{{[#"Order No."]{0},[Material]{0}}&[#"Deliver no."]})})[n])

The easiest way to do it (but not necessarily the fastest or dynamic) is to

1) Group By Order No. and Material  With Operation All Rows and name is "All"

2) Add custom column named with formula:  Table.Transpose(Table.SelectColumns([All], "Delivery no."))

3) Expand and rename your columns

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcnRy1jU0VNJRMjIxNTO3ADJMDKBAKVYHm7wpAXkzFHknkLwRUNjQ0MjI2BikkIA8kv2xAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Order No." = _t, Material = _t, #"Delivery no." = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Order No.", type text}, {"Material", Int64.Type}, {"Delivery no.", Int64.Type}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Order No.", "Material"}, {{"All", each _, type table [#"Order No."=nullable text, Material=nullable number, #"Delivery no."=nullable number]}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.Transpose(Table.SelectColumns([All], "Delivery no."))),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"All"}),
    #"Expanded Custom" = Table.ExpandTableColumn(#"Removed Columns", "Custom", {"Column1", "Column2", "Column3"}, {"Column1", "Column2", "Column3"})
in
    #"Expanded Custom"