How to save a slide show program as a video presentation for your smartphone?

I have designed a slide show and would like to save the presentation as a video so that I can send it via WhatsApp. I selected MP4 file and transferred the file from the laptop to my smartphone. Unfortunately, my smartphone does not display the file. What can I do?

The following files are possible:

MP4, M2TS, AVI, MPEG, WebM, MOV and MKV.

MP4 videos run on the phone.
I'm assuming the wrong location has been chosen.

If you want the video to appear in the gallery, do the following:
In Explorer> This PC, double click on your mobile phone display> Phone> DICM>
Paste the video into the Camera folder…

You are the greatest! 🤩

I saved it in a picture folder on the laptop, but on the smartphone it was actually in the folders under videos.