Click on the bell icon, then right click on the ground and a callout UI should appear.
On the bottom of the UI there are preset callouts.
In basics:
Police callouts:
If transporting is needed include 1/2 police cars, otherwise just security
Medical:
Medical first responders, if something like a heart attack a doctor and a ambulance.
Fire: The fire units from the airport you need, a engine and chief from the "outside" fire department MUST be included in every call. If you still have doubts watch some of his live streams, he explains it there also
Pick it up with the security guard / EOD guy (depending on what the package is), then put it back in the trunk of your car. You have to manually select the second hand button to pick it up.
Try using a different browser, with google chrome don't have any problems, Otherwise i believe its a ZIP file so try to open it with windows maps (right click, open with, map etc.
Treath levels,
Level 1 should be on default, no officers, no treath.
Level 2, more treath spawns some more officers etc..
Right now it doesnt really serve a porpuse expect it being cool, since you cant really use the officers without getting them stuck