If you are using Syncplify.me Server! version 1.x or 2.x, the first time you run the Configuration Manager, after installing the software, it displays a little “hint” regarding the default username and password to use at your first access.
Password: [there is no password, just leave the field empty]
As soon as you perform your first access, you will be required (it’s mandatory) to set a password for the admin user. This requirement is necessary for obvious security reasons.
Instead, if you are using Syncplify.me Server! version 3.x (or greater), the admin username and passwords are the ones you have chosen and set upon creation of your server instance. So there is no default value anymore, you will have to log in using username/password that you have set when you have created the particular instance you’re trying to access.