Alerts can be used as a workaround for autotrading on the broker platform that supports this feature. However, as autotrading is not available on TradingView, I am afraid it is not possible to link the system or Strategy Tester with the brokerage account.
We are considering implementing this in the future, but can not provide any ETA.
If you have a bot, that can close and place positions according to the alerts it gets, you can create an alert and tick the Webhook URL option and fill in your bot web address.
To learn more about Webhook URL, please follow the instruction.
You can find a list of third party order automation services here.
Please note that TradingView is not affiliated with the services in that list.
And I would like to stress that as this is a workaround, not full-featured auto-trading, we do not guarantee the implementation of trade operations.