Empty the tray completely, wash it in hot water with a little washing-up liquid, dry it thoroughly and fill it with clean litter.
Most cats will not use a dirty tray - you may believe it is clean, but if the cat can smell that it isn't, you will not convince her to use it.
Female cats in my experience are far more fussy about the state of their trays than males. Probably because like women, the female cat is more likely to get a chill on the bladder or any other urinary infection than the male.
Next point: if the poor cat does have a uninary infection she may be trying to tell you so, by weeing outside her tray!
Put newspaper down and scrutinize it - if the stain is darker than it should be or looks like it contains a smear of blood - then you and the cat are on your way to the vet ASAP.
She may just be stressed at moving to a new home.
Did she go out in her former home? If so, she may, like my cats, only ever have used the tray if she was desperate overnight and be trying to get you to let her out.
Which of course, you can't do until you know she has settled in, and knows where she lives now, if indeed you are prepared to let her go out.