How to fix "Invalid OTP" error during setup
In order to ensure the utmost level of security, the web-based portion of the setup process must be completed within 5 minutes; taking longer than that will result in an "Invalid OTP" error, and the setup will fail.
If that happens there are 2 possible ways to fix the situation.
Workaround #1
Fully uninstall Syncplify Server! v6 from the Windows Control Panel or, if it's Linux, using the setup CLI, then reinstall the software anew (fresh, from scratch).
Workaround #2
Run a terminal (cmd.exe, PowerShell, or any terminal/shell in Linux), then change directory into the folder where the software is installed, and type the following:
For Windows (as Administrator):
.\ss6-webrest.exe genssc
For Linux:
sudo ./ss6-webrest genssc