Thanks for reaching out. You can use the combination of multiple artboards with time triggers. Please try that and let us know if this helps or if you need any further assistance. You can refer to the following example:
I guess I need to start this off with a 'Time Trigger'. Time isn't listed on my Trigger's in XD?
I found the 'Time' trigger, and managed to created to loop animation.
Glad to hear that! Feel free to reach out if you need any further assistance.