DLC content and save data is not going to work if your Dying Light physical disc is from a different region to the one assigned to the original disc you owned before and to your PSN account. The DLC will download, but then appear as "waiting for install", not allowing you to actually install it.

For instance, if your disc has the US region code, but you have used a DLC code on a UK PSN account, or you have purchased the Season Pass at Playstation Store UK, those DLCs will simply not work.

In order to verify which region code your disc has, check its "CUSA" number against the following list:

Dying Light Enhanced Edition JP -  CUSA-04298

Dying Light Enhanced Edition EU -  CUSA-03991

Dying Light Enhanced Edition BR -  CUSA-03977

Dying Light Enhanced Edition US -  CUSA-03946

Dying Light EU-2 - CUSA-02010

Dying Light JP - CUSA-01090

Dying Light BR - CUSA-01473

Dying Light EU - CUSA-00050

Dying Light US - CUSA-00078

See also:

Can't play The Following - it goes to the regular campaign in the Slums