Every once in a while, Final Fantasy XIV offers a free login campaign to those that have not had a valid subscription for a specific amount of time. This time, until November 23rd, players can log into the game to claim 96 hours, or four days, worth of playtime.
However, like many other of Final Fantasy XIV's login campaigns, this will only be available to those who are classified as a "Returner." This means that you would have to have purchased the game and registered it on the Mog Station, you currently do not have a valid Final Fantasy XIV subscription, and you have not had a valid subscription for at least 30 days.
If all those conditions are met, you can claim the free game-time. Do note that once claimed, the clock will start ticking, and you will only have four days to play the game no matter if you are logged in or not.
Final Fantasy XIV is currently available on PC and PlayStation 4. It will be available for the PlayStation 5 as well once that is released.