Is there a way to stop android from creating folders on the SD card such as "Android" and "Download". I have Android version 8 In sd card folder of android is automatically created always, is there any to stop it?
Without tricks, the answer is No.

These "Shell Directories" are hard-coded into Android and get created automatically if any of them is found missing. You cannot prevent this behavior from happening, but there are workarounds that makes the directory creation fail, by putting a file with the same name in the same place.

See Why do Android create &quot;Shell Folders&quot; automatically? Can I change the shell folders?