After looking at  the pdf I made a few changes to the code.
They use a 40 period ATR. Their stop NEVER gets reset.
They use more data than We can,and They adjust for dividends,etc.
You can increase your data to max in "Settings > Data Manager".

The original code would reset the stop after a stop was hit.
That may work if you trade shorter term.

Add indicator - Average True Range Period 40 to chart.

Add realcode RULE with this code:

'# ATR = indicator.AverageTrueRange

Static RatchetStop As Single
Static RatchetStop1 As Single

If isfirstbar Then
 RatchetStop = 0
 RatchetStop1 = 0
End If

RatchetStop1 = RatchetStop
If CurrentIndex > 40 Then
 If Price.Close - (10 * ATR.value) > RatchetStop Then
  RatchetStop = Price.Close - (10 * ATR.value) 
 End If
 
 If price.Close < RatchetStop AndAlso price.Close(1) > RatchetStop1 Then 
  pass
 End If
 
End If

Indicator

'# ATR = indicator.AverageTrueRange

Static RatchetStop As Single

If isfirstbar Then
 RatchetStop = 0
End If

If CurrentIndex > 14 Then
 If Price.Close - (10 * ATR.value) > RatchetStop Then
  RatchetStop = Price.Close - (10 * ATR.value) 
 End If
 
 plot = RatchetStop
End IF

Not familiar with ATR ratchet stops, but here's My stab at it.

Add indicator - Average True Range Period 14 to chart.

Add realcode RULE with this code:

'# ATR = indicator.AverageTrueRange

Static RatchetStop As Single

If isfirstbar Then
 RatchetStop = 0
End If

If CurrentIndex > 14 Then
 If Price.Close - (10 * ATR.value) > RatchetStop Then
  RatchetStop = Price.Close - (10 * ATR.value) 
 End If
 
 If price.Close < RatchetStop Then
  RatchetStop = 0
  pass
 End If
 
End If

To see where the stop is, Add INDICATOR with this code:

'# ATR = indicator.AverageTrueRange

Static RatchetStop As Single

If isfirstbar Then
 RatchetStop = 0
End If

If CurrentIndex > 14 Then
 If Price.Close - (10 * ATR.value) > RatchetStop Then
  RatchetStop = Price.Close - (10 * ATR.value) 
 End If
 
 If price.Close < RatchetStop Then
  RatchetStop = 0
 End If
 
 plot = RatchetStop
End IF

Left click indicator and check "Show last indicator value"