This gateway lets you use your own Telegram account from the corporate network. To protect the network:
Attachments are scanned (antivirus, file-type rules, document checks) before you can open them.
Files you send are scanned and checked for sensitive data before they leave.
Links are checked when shown and again when you click them.
What is logged: scan results and metadata (file hash, type, size, link domain, verdict, time).
What is never stored or logged: the text of your messages. Admins can't see your chats.
Clean files are deleted from the gateway after a few days. You can unlink Telegram at any time;
the gateway also appears in Telegram → Settings → Devices, where you can end it.
Link your Telegram
The administrator hasn't configured the Telegram API credentials yet (TG_API_ID / TG_API_HASH).