All CoreMelt Plugins are now installed using CoreMelt Manager application. These older installers are for users using versions of macOS older than Catalina.
The download link on your order download page contains an installer application. Please download this in to convenient location, then quit Final Cut Pro X and Motion before running the installer.
Click continue through each stage of the installation process
After the installer has finished your new plugins will appear in the relevant library in FCP X and Motion eg titles, generators, transitions and effects. All CoreMelt plugins start with the prefix 'C2', eg 'C2 Lock & Load'.
Please note that some effects are found in generators, such as the TrackX plugin Track Layer
|Effects and Transitions are in the bottom right corner
|Generators and titles are in the top left in the library
In Premiere Pro and After Effects the effects Appear in the effects library and menu respectively.