First, let's admit that most normal humans will never use this.
Second, Hiren or Sergei Strelec's ISOs will do most of what anyone would ever need.
But, if you have to try Medicat, this works.
2025-08-14 If I did it today.
Skip the Medicat install file (I see not need for it)
Download the Medicat.zip full file.
Use Sharex to validate the hash
Plug in the USB
Exclude the USB drive letter from Defender.
Use Sordum ExcTool and leave it open to remember to reverse exclusion when finished.
Even then, Defender might turn itself on. It's hard to kill it.
Run Ventoy2disk and install Ventoy on the USB
Open Medicat.zip in 7zip and extract to the Ventoy USB
It should now work.
It's best to have other ISOs ready to add before ending the setup.
If and when adding ISOs to Medicat later:
Turn off Defender's Real-Time protection
Insert the drive
Exclude the drive because Windows Real-Time Protection sometimes turns on for some reason.
Copy the ISOs and remove the drive
Restore original settings.
Remember. A Meticat USB can not be inserted before turning off Real-Time Protection
Or boot to Meticat USB and copy or download ISOs from within Medicat.