It doesn’t have a good option for English so it makes it very hard to know what’s going on. Not very easy to figure it out at first. If you’re taking the tram/guagua(bus) in Santa Cruz purchase in the “area metropolitana” option on top and then scan the QR code you’ll find inside the tram/guagua to validate it. If you are going to another municipality get the “toda la Isla” option on the “purchase €” category and pick the line you’re going from and to. Good luck!