local poller on fortigate is very limited feature. It scans just a couple (literally) event IDs, it doesn't support NTLM, it can't do workstation checks... and it also doesn't work very well.
I honestly suggest you to use standalone FSSO CA (advanced mode, polling with WMI). It is mature piece of software and works in very large environments.
Unless you are adventurous nature, or you want just something to play with, don't go for local fortigate poller.