Alert: these are not Cryptovoxels parcels. User names and avatars in Cryptovoxels are an ERC721 token. You can mint yourself any valid name just for the price of gas. Cryptovoxels names are displayed above your head when you're in world, and displayed instead of your wallet address everywhere on Cryptovoxels that parcel owners are listed.
To access OpenSea, please switch to the main Ethereum network or the Rinkeby test network.