There are 2 possible reasons why you've activated SPayLater but are unable to check out with SPayLater.
Your SPayLater account has been suspended because you missed a payment. To lift the
suspension, you need to pay your SPayLater bills. Go to the Me tab > select My SPayLater >
Select Pay Now > select a payment method > select Confirm > proceed with the payment process.
Check that the total purchase value of your basket is within your Available Balance.
If the above does not apply and/or the problem still persists, you can contact Shopee Customer Service via chat directly with our live agents via the Shopee App.
To chat with our live agents, go to the Me tab > click Chat with Shopee.