Blend files are specifically designed to be useable by any version of Blender, but odd things still do happen from time to time.
At this point, I think we need more exacting information about the entire process you used to get and open the blend files.
What OS are you using? What web browser are you using? Do you have any unusual configuration options? Where exactly did you get the file and how did you get it? Did you right click and hit “save as…”? After you got it did you move it around any (like between folders on Windows?, or to another OS)?
I know these sound funny… but here’re my thoughts:
(1) automatic text translation may be boogering your file at some point. It can happen via your browser or when transferring between OSs.
(2) Windows has been known to mess-up when moving files…
(Best course: right click and press “save as” and every move after that should be in binary mode… if you know what that means…)