first
go to maintenance --> license in the web ui of the firewall to activate the license
second
go to maintenance --> Update center and and check to enable automatic updates
third
go to IDP/IPS --> IDP rules and build your rules to apply signatures.
I suggest you to read and search to understand the details of the signatures before applying it, they only apply and are effective if you use it to scan appropriated protocols otherwise you can obtain false positives and useless overhead to the firewall, you may need some skills or aknowledge of security threads to understand how and when use the signatures.
Always its best to configure audit mode to monitor performance and logs before apply protect mode.
Take your time, A IDS not sets up in 15 minutes, hours of work are needed to reach good setup of rules that secure the network and avoid false positives, which can be annoying to he network users
Good luck and share your experiences to get the best of our DFL products