If you owned Bitcoins on block number 507850, ~February 5 2018 and your Bitcoins were not at an exchange, then just download
and install the Bitcoin 2 Core Wallet.
You can then either import your Bitcoin private keys (Click tools -> debug console. Type: importprivkey your private key -> press enter) or copy your Bitcoin wallet.dat file (might not be compatible) to where the Bitcoin 2 Core Wallet is installed in order to claim your Bitcoin 2s.
If you are worried about the safety of doing so, you can: First move your BTC to a new address, then use the private key from the "old" address (which now has 0 BTC and thus cannot be stolen) to claim your BTC2.
Please note that Segwit (Bech32) addresses are not supported and cannot be claimed.
If your Bitcoins were at blockchain.info, see this tutorial on how to get private keys from blockchain.info
If your Bitcoins were at an exchange, then ask your exchange to list Bitcoin 2 and credit you the balance.
Let it fully sync in order to see your BTC2 balance. Tools - Information should report more than 60000 blocks.
Only download the Bitcoin 2 Core wallet from this website or from the github of Bitcoin 2