Error [Assign: Expression Activity type 'VisualBasicValue`1' requires compilation in order to run. Please ensure that the workflow has been compiled.]

HI @RPA_Innovation

Try with this expression

String.Join("parameter",Directory.GetFiles(FolderPath,"*").OrderByDescending(Function(d) New FileInfo(d).CreationTime).Take(1))

This might be Double Quotation issue

Check out this thread

Regards
Gokul