The reference typically refers to a specific mod file for Skyrim Special Edition known as CBPC - Physics with Collisions . Context of "21224"
Ensure you have the correct version of SKSE (Skyrim Script Extender) installed, as CBPC is highly dependent on it. 21224 rar
Corrupt downloads are common for .rar files; try downloading the file again from the CBPC Nexus page. The reference typically refers to a specific mod