: Choose the preset that most closely matches your model's anatomy (e.g., use the Allosaur rig for a T-Rex).

In Blender, go to > Preferences > Add-ons (or Get Extensions in newer versions).

Based on the filename fragment you provided, you are looking at the for Blender . This is a companion asset pack for the famous Auto-Rig Pro add-on, which is one of the industry standards for character rigging in Blender.

Skips the manual labor of building skeletons from scratch.

and search for "Auto-Rig Pro" to find its installation path. Add Presets: Navigate to the armature_presets folder within the Auto-Rig Pro directory on your computer. Extract Files: Copy and paste the contents (your new rig files) directly into that folder.