Can you share us a sample input and expected output
Assuming the input like below to be yours. I have done the flow:
→ Read Range Workbook

Output: dt_Input
→ Use Below syntax in Assign:
dt_Output = (From row In dt_Input.AsEnumerable()
Group row By Name = row.Field(Of String)("Name") Into Group
Let TotalSalary = Group.Sum(Function(x) Convert.ToDouble(x("Salary")))
Select dt_Input.Clone().Rows.Add(Name, TotalSalary)).CopyToDataTable()
dt_Output is of DataType System.Data.DataTable
→ Write Range Workbook dt_Output.

BlankProcess17.zip (46.8 KB)
Input Sheet is Input and Output sheet is Output.
Regards