GarageBand plugins
*I really don't know much about the subject so bear with me please*
I downloaded some plugins (Soundmagic Spectral, SonEQ, Podolski) to my macbook pro for GarageBand 10.1.0. recently, but can't figure out how to install them. I download the plugin as a ZIP archive, and once I unzip it, it produces a .pkg file. Once I double click the .pkg file, it goes through an installation process, but then nothing else happens. I have been reading up on how to install plugins to GarageBand, and it looks like I am supposed to be getting a .dmg file and then I can place it in the appropriate folder to have it visible in GarageBand.
If someone could please just talk me through what I'm supposed to do/what I'm doing wrong, I'd really appreciate it.
Thanks
MacBook Pro with Retina display, OS X Mavericks (10.9.5), 8 GB 1600 MHz DDR3