To get started, you need to create a Coinbits account using your email address. Even though you can make a Coinbits account with only an email address, you won't be able to do much with the app until you complete "KYC". KYC, which stands for Know Your Customer, is required by the U.S. government for companies that offer certain types of financial transactions.
Once you complete KYC and your identity is verified, you may securely connect an external bank account to your Coinbits account. You may then use this account to purchase bitcoin with Coinbits. This will also be the account to which cash will be sent to if you cash out your bitcoin.