Julie here from Shopify Support.
Have you already signed up for a Shopify store? If so, you can view the payment providers that are available for use in Settings > Payment providers. From there, you should also PayPal Express listed as an available option under Express Checkout, with the option to activate it. To view credit card providers, you'll want to select Choose third party provider, where you'll see a list of payment gateways that you can use alongside PayPal.
Feel free to let me know which options are available for you! I'm curious to know which one you decide to use.