Load the game on your PS3, then select the save option from the menu and choose Cross-Save. Once the game has successfully saved the game in the cloud, load your PS4 game and select Load Cross-Save from the main menu.
Please note that cross-save is only compatible between digital/digital or physical/physical version of the game.
Hope that helps.
Rainbow Skies is finally available. Download it on the PS Store for PS4, PS Vita and PS3.
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