When I arrived (early Oct, 2022) there were groups of people everywhere waiting for their overdue Ubers, so I took the metro. The station is in the airport, follow the signs, go downstairs to find the ticket machines on the left.
I used my US credit card to buy my Viva Viagem card there and put 20 Euros on it, which still had money left after my 8 days - I walk a lot.
You can take the red line from the airport to Sao Sebastien station, change to the blue line towards Santa Apolonia and exit at Terreiro do Paco, which is 350m from Praca do Comercio. Check the map to see if other routes/stations would put you closer to your lodging:
https://www.metrolisboa.pt/en/travel/diagrams-and-maps/