I have looked high and low on the 'Net and have been unable to even find a single reference to Package-Manager. Yet, when I type in Package-Manager.net it goes directly to a Fed-Ex, USPS, UPS page and says the "Must have app for tracking packages." When I scroll to the bottom of the page there is an Uninstall button. That just takes you to a page that shows you how to get rid of extensions. It is just NOT there in Extensions, nor is it in my Programs and Features. I am not finding anything that looks out of place.
The pop-up appears as a large 3"x 3" gray block that pops up in the lower right-hand corner of the desktop even when Google Chrome has not launched, but appears most often when I am using the "Net. You literally can't go forward until you click the arrow to send the box to the margin of the page. One time I actually clicked on it, and it took me to a web page selling Male Supplements products. So it may track packages, but the big gray box is just click bait!