There are several ways to install and manage Cyclops but the easiest way is by using the aescripts + aeplugins manager.
Window > Extensions > Cyclops.<aside> ⚠️ Manual installation is really only used by extension developers and is offered here only as a last resort.
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Change the extension of the Cyclops.zxp from .zxp to .zip.
Unzip this newly created Cyclops.zip to get a folder called Cyclops.
Navigate to the Adobe extensions folder.
macOs: /Library/Application Support/Adobe/CEP/extensions
Windows: C:\Program Files (x86)\Common Files\Adobe\CEP\extensions
Copy the Cyclops folder to the extensions folder.
Close and restart After Effects.