The only 5 pin rotary encoders I have encountered used 3 for ‘encoder’ part and the other 2 pins were for a momentary push button in the shaft; I haven’t seen one that names a ‘CLK’ signal etc. I’m trying to see activity in the serial monitor. The encoder in question is a Kubler.
None of the encoders in that data sheet have a “CLK” signal. They are either standard quadrature (some with a reference signal that may indicate a home position or something similar) or RS422 (which likely come out as A and B)
The error is in assuming it generates signals that the serial port understands. If you just read the state of the digital pins connected while it is slowly turning then you should be able to see a patern. (Assuming the voltages applied do not exceed the Arduino max rated levels)