I watched a youtube video about it here- https://www.youtube.com/watch?v=Cvp-WcoKpgI
Bubble require us to input each image from the Multi-Uploader one-by-one and store the file also. Like this:
Check out this post I put up months back about how to upload multiple images at the same time using the multifile uploader and how to save them as images and not files so that in the future you can use an image element to display them as well as imgix to process them