When you installed Sandfly, a randomly generated password was created for the default admin account. This password is located on the server under the setup_data directory in the admin.password.txt file as show below.
cat ~/sandfly-setup/setup/setup_data/admin.password.txt <randomly_generated_password_here>
Copy this password and use it with the admin user to login for the first time.
You can change this password later under the user profile section.
Updated 8 months ago