Polkadot is its own network, and is completely separate from Ethereum or any other chain. Therefore, you cannot use MetaMask or MyCrypto wallets to store your DOT. You can only store DOT in a Polkadot address on the Polkadot network.

Polkadot addresses always start with 1 (as opposed to Ethereum or BSC addresses, which start with 0x..) 

There might be a Polkadot integration for MetaMask in the future, however at the time of writing we are not aware of any working plugin yet. 

If you mistakenly withdrew DOT to MetaMask from an exchange like Binance, you sent a "wrapped" token rather than the native DOT token. You can find more information on this in this article

IMPORTANT: The contract address shown on sites like CoinMarketCap, which is able to be added as an asset in MetaMask, is for DOT-pegged (wrapped) versions of the token. Don't confuse this with Polkadot's native DOT token, which always starts with the number 1.