Got the same problem in Steam with one of the errors per each try "Missing downloaded files" or "Disk write error".
This happens even while the whole Steam library is under the "Exclusions" rule in windows security
Got it solved as:
- Uninstalled F-14 DLC module from steam.
- Reinstalled F-14
- When getting the same error during a new installation attempt, go to Windows security - protection history - and restore the most recent quarantined item from the history listed as: "SteamLibrary\steamapps\downloading\223750\Mods\aircraft\F14\bin\F14-HeatblurCommon.dll"
- press retry for the DLC in the Steam download section again. Worked for me.