scanned films rejected with "QUALITY ISSUES."

Hello,

To get a better result, you will need to scan the slide with a scanner that can also scan film/slides, rather than using a digital camera. The method you used has given a colour cast - blue. It has also interfered with the exposure, so you have to make adjustments in Photoshop -  for example:

But, even if you made these corrections, it still probably won't pass, due to the overall quality.

Therefore, I wouldn't bother scanning slides with a camera, unless you have a top-quality flatbed scanner that can scan slides.