Here’s TM SGNL maker’s website. Nowhere on its front page will you find the word “encrypted”. In fact, It appears that the company’s primary product is exporting the contents of WhatsApp, Signal, and Telegram apps on a phone so they can record otherwise E2E-encrypted messages. This product can be used to spy on employees’ private communications on their personal phones.
The TM SGNL app is an “enterprise” (off the App Stores) app that captures messages from Signal and archives it. It is literally designed to circumvent Signal encryption and archive messages elsewhere.
TM SGNL product page:
https://www.telemessage.com/signal-archiver-transfer-from-ios-device/
TM SGNL installation page:
https://www.telemessage.com/signal-archiver-ios-installation-upgrade/