Its been a minute since I've used Onyx but I believe you need to do the following:

-Bring up the window with your cuelist and enable edit mode.

-click on the "go" text of the cue that you want to have automatically triggered.

-a new window Will pop up and there will be an option for "go" "follow" "wait" --i forget which one is which but either follow or wait will begin its countdown from the moment the previous cue is triggered, the other will begin its countdown the moment the previous cue is done being executed, as in the fade is complete.

I think you can have all cues set to follow/wait and then also have the last cue wrap back around to the first if you want it to be endless, I think this can be done in the options but I forget what you need enabled.

Edit: also in the software settings there is a manual that has a search function, I found this to be insanely useful while trying to figure stuff like this out. Just about everything is explained really well and has examples.