Which step are you having issues with?
By default, you should just see a reCAPTCHA checkbox with "I'm not a robot" written next to it. Just click/tap the empty square on the left, which will add a checkmark and let you in.
If the automated captcha can't verify you as not being a bot (can happen depending on what device/browser/extensions you're using), you'll get an additional verification step that may require you to identify images of signs/buses/cars/etc. Follow the instructions, select all the appropriate images (they sometimes refresh and you have to continue selecting new images), and click Verify once done.
In this one, I had to click the four bus images, then the "SKIP" button changed to "NEXT". I clicked that and had to find traffic lights in another grid of images. After that the "NEXT" button became "VERIFY" and I was let through.