There is no application set to open the document “install_flash_player_osx.dmg.mdlp”.
What application do I need?
Please delete the file and try downloading the installer again. If the issue persists, try the following:
Oh wow, blast from the past. This sounds like that thing a few years ago where having matlab installed caused Safari to append .mdlp to the end of filenames.
Anyway, most likely a Safari issue and not a problem with Adobe's website. If the matlab/Safari combination rings true, that thread is probably useful. If not, another browser would probably get the job done, but there's an underlying Safari problem that will still need to be sorted out. I'm happy to try to figure it out (it's weird, so I'm curious), but Apple is really best equipped to handle that.