Using an Environment
The details of your web application URL can be found when viewing your environment's details and also in the email you received when the environment was first created.
Please note: When an environment is newly created, it is normal for the web application URL to return a "404 page not found" error. This is because your application (e.g. Magento 2) has not been installed yet.
In the case of Magento 2, you need to install into the /app/htdocs/ directory.
The environment creation process also provisions an SSL certificate automatically. Currently, it is expected that you connect to your web application using https:// protocol.