I need my Shopify store ready to collect payments without a hitch. The account is already live; what’s missing is the actual gateway activation and the behind-the-scenes configuration. I’m open to any of the mainstream providers—PayPal, Stripe, Square—so we can decide together which one (or combination) suits my market and currency best. Here is what I expect: once you have the correct API keys or merchant credentials, handle the entire setup inside my Shopify admin, adjust checkout settings, make sure taxes, currencies, and refund flows line up, and walk me through any secondary verifications the provider asks for. Full configuration is essential, and I may also want to run a couple of test transactions before going live. If you can guide me through those sandbox charges—or run them yourself and share screen captures—that would be ideal. Hand-over is complete when I can see a successful paid order in the Shopify dashboard, customers can check out without errors, and you’ve noted any steps I should follow if I switch gateways or toggle test mode in the future.