Basically yes, because you are walking in the outdoors and the caches are accessible for free. All you need is a GPS-compatible smartphone or GPS device and a geocaching app. Beginners like to use the free Groundspeak app or the free basic functions of geocaching.com. For an affordable annual fee of around 30 Euros you can become a premium member and use many additional features and functions.
In Ötztal, all treasure hunting data is made available to you free of charge - you can find the coordinates for varied routes HERE or on geocaching.com under the name “9for5 & 5for1”.