If the exchange shows that the transfer was successful, it does not means that the transfer was a true success. Every transaction in blockchain needs to be confirmed by a miner. You can check the transaction status at blockchain.info. Go to blockchain.info to learn how to use blockchain.
If it the APP is showings a successful transfer in blockchain.info, but you didn't receive the Bitcoin in the imToken APP, please email us at firstname.lastname@example.org.
We suggest that you learn how to query transactions in blockchain.info. Bitcoin is more complex than ETH, so it may take longer to find a solution to the problem using customer service.