I was able to determine the cause of my problem.

All I have to do is to save it as a Formular, and replace the ";" with ",".

ws.Cells[4, 6].Formula = "HYPERLINK(\"#\"&CELL(\"address\", INDEX($C$2:$C$4, MATCH($E4,$A$2:$A$4,0))), INDEX($C$2:$C$4, MATCH($E4,$A$2:$A$4,0)))";

My original end of Triggering Calculations/Setting it automatic etc also isnt required.