LG Velvet 5G t-mobile buy one get one free via 24 monthly bill credits - NO new line, No add a line

Link said you have to activate 2 lines, but when you log on you dont have to.
https://www.t-mobile.com/cell-pho...R9RVB22332

How to get this offer:
1Purchase two new LG VELVET phones on a monthly payment plan. Pay any applicable tax on the pre-credit price at sale.
2Must have an active voice line for each device purchased.
3Receive 24 monthly bill credits totaling $588.00
If you cancel wireless service, credits may stop & remaining balance on required finance agreement may be due. For well-qualified customers.

review https://www.theverge.com/21304097...ecs-camera

If you cancel wireless service before receiving 24 bill credits, you may owe up to the full value of all devices (e.g. LG Velvet 5G $588.00); if cancelling your account, you can contact us first to instead make discounted monthly balance payments. Tax on pre-credit price due at sale. Limited-time offer; subject to change. Qualifying service required. $10 SIM card, and, in stores & on customer service calls, $20 assisted or upgrade support charge may be required. Discount on device of equal or lesser value. $588 via bill credits on lower priced device; must be active and in good standing to receive credits; allow 2 bill cycles. Max 6 offers/account. May not be combinable with some offers or discounts (e.g. Carrier Freedom).