PlayStation 5 Digital Edition slim storage is full or games will not install

The PS5 Slim Digital Edition comes with 1 TB of internal storage, of which roughly 800 GB is usable, and large modern games of 100 GB or more mean it fills with ten titles or fewer. Sony's guidance gives three ways to expand. A compatible M.2 SSD, with a heat sink that meets Sony's size limits, goes into the console's expansion slot under the side cover and can hold and run PS5 and PS4 games. A USB extended storage drive can hold PS4 games and PS5 games for storage, but PS5 games must be moved back to the console storage or an M.2 SSD to play. And you can free space inside the console:

Settings, Storage, Console Storage lists games and media by size, and you can delete games you have finished, because saved data stays when a game is deleted and is also backed up to the cloud with PlayStation Plus. Captures, screenshots and the game's update files also take space. You can move games freely between console storage, USB storage and an M.2 SSD. Because the Slim Digital has no discs, every game and its updates are downloaded, which makes storage planning part of ownership: a rule of thumb is to keep two or three big games installed and delete the rest, since a game you delete can be downloaded again free from your library.