You can allow your browser to send push notifications, the instructions can be found in our Help Center.
If you are using Windows 10, be sure push-notifications are allowed in here as well. How this can be done is explained here: https://help.trengo.com/en/articles/9277.
P.S. did you know it is possible to snooze these push notifications in Trengo, once you've allowed your browser to send them?