Uploader not working

Hi,
Thanks for this plugin that corresponds to what I was looking for.

I got a major issue: after creating the uploader and using the shortcode into one of my page, nothing happens. The uploader does not appear.

I can not upload anything since the front-end upload manager is not showing.
I followed this tuto: https://www.youtube.com/watch?v=R8lGqg8fkuU

Any idea where it could come from?

Thanks.

https://www.ads-software.com/plugins/closify-maestro-image-uploader-gallery-builder/