PC/Mac/Linux are currently synced to enable co-op multiplayer via Steam.
Borderlands 2: Profiles and save games are not saved cross-platform in the Steam Cloud.
Profiles and save games are not saved cross-platform in the Steam Cloud.
The same goes for rewards from Shift. They're only given to the system that they're used on, so rewards redeemed on the PC won't appear on the Mac/Linux and vice-versa.
Q: I'm missing DLCs from the GOTY or pre-order!
Borderlands 2: Unused Pre-Order DLC 1
Borderlands 2: Unused Pre-Order DLC 2
Borderlands 2: Unused Pre-Order DLC 3
Borderlands 2: Creature Dome
Borderlands 2: Creature Slaughter Dome
Borderlands 2: Premiere Club
Borderlands 2: Collectors Edition
Borderlands 2: Collectors Edition Pack
The Collector's Pack and Premiere Club DLCs can be accessed when you start a new character. Once your reach Claptrap's house, look into your inventory and the gear will be there.
For the Creature Dome/Slaughter Dome, you'll need to head to the Wildlife Exploitation Reserve from a fast travel station and those missions are near the Natural Selection Annex. You can access that point when after you reach Chapter 10 in the story line.
The pre-order DLCs should display as the Mechromancer character class, a Vault Hunter’s Relic, a Golden Key, and a Gearbox Gold Gun Pack.