@loopyogden no, you did not waste your money. i use an ES5 (actually an ES8GT expander coming off one of the ports of my ES5) to send the midi clock. You would use the ES4 controller plugin and a 1/8" to MIDI cable plugged into one of the ES5/ES8 ports. All you have to do is dial in the right port and enable midi clock on the plugin.

As for calibration, it can sometimes take a few tries. Definitely pick a simple waveform (turn down all of the FM busses on the DPO) and play with different settings of the tuning knob. I generally get the best results when it’s directly in the middle, but sometimes you have to tweak it a bit. Don’t be afraid to try multiple calibrations until you get the best one!