The issue is that your camera and the zoom have two different clocks. Next time. use a recorder with timecode.
There are several work-arounds, none of them too pretty. You can see how much off you are in the timeline by which track is longer: if the video is longer, you can try slowing down the audio. If the audio is longer, you can try speeding it up an appropriate percentage. But this is not a guarantee.
Or you can do what documentarians have been doing for over 50 years: line up the beginning, play down until it goes out of sync and then either pull out the extra track to line it up, or cut the track and move it down the timeline until you are in sync again. Do this only for critical dialogue, you can fudhe most of the rest of it either with wild track or repeating dead spots.
Like I said, next time use a proper audio recorder.