Installing Sigilium on a TSE server requires that the application be installed for all users.
Sigilium installation for Outlook for all users
Download the version available here :
https://sigilium.com/apps/sigilium.msi
Log into the TSE server as an admin and install the app for all users by doucle-clicking on it.
The users will then launch Sigilium on their workstations and follow the instructions to finalize the set up of their email signatures.