To send certificates for an institution you can register at, app.sertifier.com/en/register. Your 14-day premium free-trial will start when you open your account.
Yes, you can add up to 3 users if you have a premium subscription. If you have a premium+ subscription you can add unlimited users to your institution account.
After you log in to your account, you can add and delete users from the “users” tab on the institution menu.