Creamy garlic chicken...what temp should the burner be on the stovetop?

Personally, I would sear the chicken first, on medium-high heat, until I got the color I wanted. Then I would take the chicken out of the pan, lower the heat to medium or medium-low, let it cool down for a sec, then add the garlic and cook until it’s golden and fragrant (maybe 1-3 min, depending on heat level), Then I would add the chicken back to the pan and add the liquid and proceed from there with the recipe as written. This way you have more control over how much and how fast the garlic cooks.

I would expect to use a moderate heat setting, myself. The recipe calls for you to use boneless, skinless thighs, which should take color fairly quickly- and before the garlic begins to get too done. You will be adding water and the marinade, as well as a lid, before it should become a risk of burning. Then of course, your minced garlic will be protected from that hazard. If you needed to, there is also no reason why you could not add a little more water if it became necessary.