The following error, means your Stripe account isn't quite setup to allow for EMV/card present transactions yet.
The card_present source type can only be used in testmode
As Stripe is rolls out new features, they typically have them turned *OFF* to start. The next step to get this enabled on your account is by reaching out to their support team at:
Make sure to let them know that:
1. You purchased a Stripe Terminal card reader (BBPOS Chipper 2X BT) from Payment for Stripe (a Verified Partner)
2. You want to process EMV transactions, but are currently in the testmode_only state
3. You're unable to process EMV transactions until you are allowed to make these transactions in LIVE mode