Cant redeem purchases on Xbox

Will16

Hi,
So its probably best if I give a little backstory - basically I first brought the game when it first came out on PC, and got the Imperial edition. I played for a long time, and brought the digital summerset version when it came out as a chapter (not through crowns).
I stopped playing but recently came back on Xbox. I brought the game for £2 preowned which is what made me want to play it again, and after downloading it I linked my ESO account to my PC one (this one I am posting with, that has the imperial edition and summerset version in the accounts billing history).
However, I do not have access to Summerset, or the imperial edition stuff (race, horse, any race to alliance). This didn't bother me much at first as I actually forgot about it, but today I remembered that I had the dlc's and tried to find a way to redeem these purchases on the Xbox, but couldn't find one anywhere.
So what I'm asking is if it is possible to transfer these bonus' to my linked Xbox account - and if not, then what is the point in linking an account?
Thank you for reading

ZOS_Bill

@Will16

Entitlements are platform specific, so Summerset on PC would not transfer over to Xbox.