how to activate icontrol in f5 big-ip

You don't need to do anything to enable iControl it is simply part of the HTTPS management access.

Are you connecting from SolarWinds to the management interface or a self IP?

If a Self IP are you allowing HTTPS in the port lockdown (K13250: Overview of port lockdown behavior (10.x - 11.x))?

You can test access using curl with the following (change the password and F5 IP to match your devices)

curl –sk –u admin: https:///mgmt/tm/

As for the icrd daemons, it is a non-core service but should be running on the underlying Linux system. On Bash you can run 'ps -A' to see if it is running.