To stream live on several sites at the same time, you should specify server addresses and broadcasting key in the settings of your stream.
Click on the name of your stream in the "Live" section.
In the opened window go to the "Restream" section.
Enter your the server addresses and streaming keys. Check the "Enable" box. In the custom stream server settings you can specify any server address. If it requires additional authorization, there is an input field for login and password below. Click the "Save" button at the end of the page.
To restream to Telegram you should add port :443
to the link, then the link will have the following form - dc4-1.rtmp.t.me:443/s/
.