I'm going on a vacation to Jamaica and would like to take pictures for a group. ( 40 people ), put them on a site in a folder and give everyone access or a common pass word to access and download the pictures they would like to keep.
Yes - you could use one of several options and the only problem I can envisage is the final size of all the image files I.e., how much space you are going to need to store all the photos.
Free options include Dropbox (2GB free), Microsoft OneDrive (5GB free) and Mega(50GB free) cloud storage options. You will find other options with a simple Google search of "free cloud storage".
If you are not worried about who has access to which photos (I.e., if EVERYONE is allowed to access EVERY photo) then you will simply share a link to the photos folder via email to each person in your group allowing them access.