GTA 3 Definitive Edition was one of the free games that were being offered for the PS Now subscribers, but it comes with some issues.
Sony’s PS Now subscription is lagging behind Xbox Game Pass in terms of competition and quality of game releases, so while Game Pass subscribers were able to play through GTA San Andreas Definitive Edition with the choice of downloading or streaming these games, PS Now subscribers were offered GTA 3 Definitive Edition.
The launch of these games is planned for today as Sony confirmed the PS Now games lineup for December 2021 earlier. This is available to play now in some regions like Europe and Australia.
According to a reddit thread, there is no option to download the game at all, and it seems to be limited to streaming only for now. This is a terrible option for those who were hoping to download and play the game natively, but this might not be the end of things.
This could be a bug that could be fixed with a future update. It has happened with a game before in the past and that was resolved within a day or two, so fingers crossed this happens here as well.