Download CapCut for free, drag both videos into your media panel, now click + on them both to drop them on the timeline. Make sure the ratio (under the preview

Download CapCut for free, drag both videos into your media panel, now click + on them both to drop them on the timeline. Make sure the ratio (under the preview window) is set to 9:16. Click on each video and move it around until you have it lined up where you want it. Export.