An alert will be triggered only when price breaks and closes beyond the specified prices. You will get an alert on the first candle that closes beyond the levels you set.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.
I frequently use the normal alert functionality and can easily create a trend line and program it to alert me when it's crossing, either up or down. Where I'm having an issue is getting your script to alert with a close on the desired timeframe. Under the first condition option do I select your script "BKOI" or the trading pair itself? I have tried different variations of the options to no avail.
You need to manually set the alert to trigger for each currency pair and timeframe that you set it up on. Good luck and let me know if you need further help :)
Please check your direct messages.