I am lvl 30 and I have combat index 48 I am ready, and I have the subscription of all accesses and it says that the dlc is granted but I don't know how to enter or play it
You should have a mission in your journal to direct you where to go but the teleporter to Central City is in the hangar of the Watchtower tech wing.
Just FYI you need combat rating of 53 to enter the Central City open world. I believe the Flashback duo is the only thing available to you at the moment.
