There are purple spots inside the freezer that look like mold, but I'm not sure. Is it safe to store food in there?
Thanks for the picture. (Worth 1000 words.) Those spots aren't what I was imagining when you said purple. They look just like what I was imagining when you said mold, though. Or maybe I would call it "mildew".
Anyhow, my advice: do clean it, with wet baking soda & rinse with water, like people say you should clean a refrigerator. If the stains remain, which I bet some will, try and remove them with a bleach solution, then rinse that off. If stains still remain, which I bet some will, then they're just stains at that point. Don't pay any attention to them....Don't put food in direct contact with the floor or walls of the freezer (of course). Wrap food well or enclose in proper containers when you freeze it, and it will be OK. The situation sounds temporary anyhow.
FYI: Because it had been unplugged and left outside for a few months before we got it, our refrigerator retained a slight musty smell inside even after we cleaned it as best we could. Our food however was fine. We just stored it wrapped as we normally would, and we had no issues with off-odors or spoilage in the food. The smell in the fridge's atmosphere persisted for many weeks though, until one day, we realized it was gone. No, we didn't just get used to it; the smell had completely dissipated. But it took a while.
From the photo, I can almost guarantee that is mold. Depending on the species, mold spores, mold mycotoxins, and mold-emitted VOC's can all be hazardous to human and animal life.
By the extent of the infestation, there is a good chance that the mold has spread into the areas of the freezer that are not visible.
My recommendation is to not expose people or animals to that freezer and never to store food in it.
If that is not an option, disassembling the freezer and cleaning all components with a borax-based cleaner (while wearing an appropriate respirator) could possibly reduce the problem.