A ‘texture collection’ of jpgs is not the same as a SketchUp collection. Image files need to be converted in to .SKM files.
This is done by importing an image into a SketchUp model, name the texture and save it (it will be saved as .SKM)
This process could be automated if you have lots of jpgs to convert.
Users should not have to do this over and over again, they could just ‘open a collection’ of previously created collections
Check out this thread:
How to set up Trimble Connect for libraries
A quick and dirty way I sometimes use is to insert a component with all the Materials and Tags, but as said, this would bloat the file unnecessary if you do not purge regularly.