Just wanna make sure, if it says...

I just want to make sure, if it says you "must make a pick by the 16th", does that mean I can pick a game on the 16th, or is the 15th the latest I can pick? Seems like the 16th is okay but I'm not 100% sure on that. Cheers...

In your case, the game has to be played on the 16th at the latest.  Even though the wording only specifies making a pick by that date.  Still don't know why they haven't changed this ambiguous statement after so many confused participants.

Just know you have 7 days from the time of your last pick to the time of your next pick before your streak gets erased.  So if you make a pick on the 7th of the month, your next pick must come on or before the 14th.  If it doesn't, your streak is erased.