you should usually unzip a Package, and check first, what's in it, then, upload an unzipped Package to the server.
But this all depends on, what you are uploading, because
OcMod's are handled differently to
VqMod's and other File-based Extensions, when it comes to install them on the Server Shop.
And if you upload something by use of the OC Extension Installer, it's usually an
OcMod, and this one should, usually, be clicked on, from the PC, to be installed, but NOT uploaded as ZIP to the Server, it cannot be found there by an OcMod Installer. In addition, not all OcMod's act according regulations, when it comes to install them, some even don't even contain everything on files/infos, required, to make 'em work. Just to mention this...
To give you some ideas...
Ernie