"easy", You have to open the chests to get 2 of the event cards to fuse them which mean +2k viagra and 8/16 hours of research so it stops you the first day unless you pay. (maybe it should work with other events... but it didnt worked with checkgirl)
This + the quest u says and probably others makes this a pay to play event.... or bad dissigned one.
EDIT:
there was different event last month, I started this one yesterday. And looks like events last for a month but u can only participate 7 days