Automatically save QuickTime Recording

Question

I'm trying to automatically save a Quicktime recording to a directory with an specific file name including date and time.

To create the path, the I created a input dialog to create the folder and a subfolder with the date.

tell application "Finder"
    activate
    set DateStamp to short date string of (current date)
    set patientname to text returned of (display dialog "patient name:" default answer "")
    set folderpath to POSIX path of (choose folder with prompt "choose folder")
    
    do shell script "/bin/mkdir -p " & quoted form of folderpath & "/" & quoted form of (patientname) & "/" & DateStamp
end tell

Then I open Quicktime and start the Recording. After stopping the recording, the new record should be saved under the specific name + date + time in the new created subfolder.

tell application "QuickTime Player"
   activate
        
   repeat
            
   set tdoc to new movie recording -- document "Movie Recording"
            
   say "Ready!"
            
   delay 1
            
   repeat while exists tdoc
    delay 1
   end repeat -- the recording is stopped
            
   say "Stop!"
            
   tell front document
    set TimeStamp to time string of (current date)
    set fileName to POSIX path of folderpath & "/" & patientname & "/" & DateStamp & "/" & patientname & "_" & DateStamp & "_" & TimeStamp & ".mov"
    save it in POSIX file fileName
        close
   end tell
            
   end repeat
    
end tell

After saving the new Record should close and a new recording window should appear.

However, there is always an error saying, I have no writing permission to save the file.

screenshot

What do I have to change? i have no idea.

Although I have to say that I am very new to apple script. thanks in advance!

PS: I'm Using QuickTime Player Version 10.5 (1148.4.1) and MacOS Ventura 13.0.1