To get to Piazzale Roma from the airport the cheapest method would be to take the Venice Express bus. The cost of a one-way ticket is 8 euro and for a round-trip ticket the fare is 15 euro. Piazzale Roma is the end of the line for land vehicles in Venice. From here it’s either walk or take a boat. Fortunately, your hotel is only about a 5 minute walk from Piazzale Roma. I went to your hotel’s website and they have walking directions, which I have copied and pasted below. With just hand luggage it should be an easy walk, although it is always easy to get lost in Venice. Best of luck.
From Piazzale Roma: Suite in Venice Ai Carmini Residence is reachable on foot (about 5 min. see also map).
At the crossing of the bridge “Ponte dei Tre Ponti” continue to Fondamenta Tre Ponti straight to Fondamenta Cazziola and at the end of this pass the bridge, after the bridge keep right, and after about 20 meters continue along calle dei Ragusei along it (50 meters), turn left (15 meters) pass the bridge and keep the right you are now in Fondamenta del Soccorso continue for 30 meters and you have arrived at number 244 of the Residence ai Carmini.