As you are purchasing Arculus and have continued to the payment screen, select the "BitPay" radio button. Please check that you agree to the Terms and Conditions and then press the "Continue" button. This will bring you into the BitPay application to proceed with payment. You can choose which wallet you will be paying from. You can select WalletConnect or choose your preferred wallet from the list available. Follow the instructions for the wallet you select. You will choose which cryptocurrency you hold in that wallet to complete your purchase. Scan the QR code and complete the transaction. If this is your first time using BitPay, you may need to create an account. If you've previously used BitPay and have an account, you may need to sign in. 

Your Arculus purchase will pend in "awaiting payment" status until the transaction is confirmed on the blockchain. Please note that payments using BTC take longer to confirm and it may take an hour or two to receive your order confirmation email from Arculus.