There is nothing about mulch that is attractive to ticks. They don't hide in it, don't sleep in it, and aren't attracted to it, don't nest in it. A layer of mulch can even be a barrier against tick invasion.

They typically use vegetation for their host questing locations, sometimes waiting patiently for a warm blooded animal (like us) to come strolling by or actively pursuing the scent of CO2 that surrounds us.

I'm not so sure that I would come right out and say that mulch 'repels' ticks, but it can be a big help in keeping them out of areas where you wish to be.

Look for ticks in in any kind of vegetation, including over story trees.