Where to find it
Open your journal and go to the Rewards tab. Each run of rewards is a row of boxes, one for every day. Runs come and go, so there may be one, several or none on at any time, and a run can last a week or much longer.
Claiming
You can claim the first box straight away. The next one unlocks at the daily reset, and a countdown says how long that is.
Missing a day costs you nothing. Come back and claim the next box, and the run carries on from where you left it. You cannot claim two days at once.
Every box shows what is in it before you open it: experience, gold, items or a mix. A claimed box is ticked, the one waiting for you is ringed, and the ones still to come are dimmed.
A finished run stays on the tab for a little while so you can see what you got. If your bag is full when you claim, what does not fit is not lost.

Next: back to the guides.