You have reached the end of the "playable" portion currently stored on your drive.

If you are using a disc, ensure the whirring sound has stopped, indicating the console is done copying data.

Alternatively, check your to see if a patch is currently active.

Downloading happens significantly faster when the game is not running. Close Days Gone entirely and put your console in Rest Mode to prioritize the download.

On physical copies, the disc may still be copying data to the hard drive, even if the progress bar isn't immediately visible. How to Fix "Download Incomplete"