to login your Thonem Administration Panel you have to follow the installation URL and append /admin to it, below some examples of the installation URLs and how to append the admin URL
Installation URL: https://www.example.com/en/
Administration Panel: https://www.example.com/en/admin
Installation URL: https://subdomain.example.com/en/
Administration Panel: https://subdomain.example.com/en/admin
Installation URL: https://www.example.com/subfolder/en/
Administration Panel: https://www.example.com/subfolder/en/admin