if your having problems installing this addon then you've come to the right thread :D

TIP #1:
make sure you have launched the ORIGINAL LAUNCHER not the one you downloaded, then wait for it to download the addon
(im thinking this is where many people get stuck)

TIP #1/2:
if you've already launched the original skyrim after subscribing to the addon then do this:
when the launcher is opened (not the actuall game) click on 'Data Files' then make sure the addon you want is checked
(also probably another place where many people get stuck :L )

FINDING THE TARDIS:
if you've done this then when your in the actual game and spawned in, bring up your journal and there should be a new quest called something like 'The Blue Box' (i dont remember but something like that :L) then click it (to be able to see the marker and stuff).
and look on your map around whiterun

hope this helped

if anyone needs help or help with other addons just add me or something

:L