2 videos need to be merged together

As part of a training session which I did on ZOOM, I recorded it - however it's as 2 parts and I'd like them merged together as ONE video.

This is the first small job. The total duration of both videos is 2 hour.

I do have a 2nd job but this job is the most important. Needed within a day ideally by tomorrow morning! I have the video files downloaded.

I'm confident this won't be a long job - 1 hour maximum.

I can send the files.