The DLC will be available as part of the March login rewards campaign, and ZeniMax really wants you to have it because you only have to log into the game twice during the month of March to claim the DLC for free, from March 4th-April 1st.
If you do, and you haven’t played through it yet, you have a little time to catch up before the next chapter, Scions of Ithelia, is released. There’s some very relevant content in Orisinum that will tie into the new chapter, including Maelstrom Arena.
The Elder Scrolls Online 10th anniversary celebration is going to kick off in earnest in April, but you can get a jump on all that.
You can also earn some bonus collectibles in the Orisinum DLC. Complete the main questline, earn the Kingmaker achievement, and claim the Inkfur Ursauk mount.
All of these items will be collectible through April 1st. You already got those achievements and you own the DLC, you can also claim these extra items without having to do anything after March 4th. See details at The Elder Scrolls Online.
