Hi
Sorry for the inconvenience caused.
To isolate the problem...
Open Windows Defender Security Center
Click Virus & threat protection
Click Virus & threat protection settings
Scroll down to Controlled folder access
Toggle it off
in later versions
Open Windows Defender Security Center
Click Virus & threat protection
Click Ransomware protection
Toggle off Controlled folder access
Also in Windows Defender Security Center
Open App & browser control
Set 'Check apps & files' to off
If the problem persists, could you confirm if this also happens in the default Administrator account?
Open Start
Type: cmd
Right click CMD
Click Run as administrator
At the command prompt, type:
net user administrator /active:yes
Hit Enter
Close command prompt, restart, then try signing into the Administrator account.
Try downloading your Adobe PDFs again.