Ask about "save this payment" AFTER payment, on receipt page.
If you ask about creating account after instead of before (or perhaps during: with a checkbox for "save payment method") you'll likely get more takers. We're all used to "save this payment method" and the likely "create an account" that will happen LATER. But a link ... that implies you're taking me to a new page and I'll likely have to start over.
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William Conley
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