Has anyone had trouble with corrupt files downloaded from the Captivate Assets library?

I recently started using the Captivate Assets tab to access the scenarios and cutout people via the elearning brothers library. I was able to download multiple versions of two cutout people no problem and they appeared in my "characters" option under the media tab in Captivate. However, when I tried to download additional people, they do not appear anywhere in the program. So I went to my own computer hard drive and found them in my shared assets folder, but all the .png files say they are corrupt. Even the initial two characters that I had previously accessed successfully from the media tab are saying they are corrupt .png's. 

Any ideas of what may be happening? Let me know if you need more information and specifically what information would be helpful to you in solving this! The specific message I get when I try to open a .png is :It may be damaged or use a file format that Preview doesn’t recognize. Also I checked the permissions and I should have read&write access. 

Thanks!