You can access ESO Plus unlocked DLC through the Stories tab of the Collections menu.
- Open the Collections menu.
- Select the Stories tab, which is the icon in the middle that looks like an open book with an arrow (see image below)
- On this tab you will see a list of all of your available Chapters and DLC, sorted into Dungeon and Zone categories.
- Simply select the DLC you wish to explore to see the option to accept the starting quest for that area.
If you are still unable to access DLC after following these steps, please contact customer support for additional help.