Following This guide, you can configure payment gateways and get required credentials (keys) from their console, which you can use into your projects. so please follow this guide carefully and collect credentials

Go to Stripe Dashboard

Click Developers

Click API keys , shown below and you got Publishable key and Secret key .

Go to Razorpay

After successfull login go to Account and Settings

Click API keys , shown below and you got Razorpay Key id .

Go to Paystack

After successfull login go to Settings > API Keys & Webhooks shown below

Go to Paypal Log in to Dashboard

After successfull login go to Apps & Credentials and Create App

After Create App you got Client ID and Secret Key

Go to Flutterwave

After successfull login go to API keys section, you got Public key, Secret key, Encryption key.

Go to SSLCOMMERZ

After successfull login, You get your Store Id and Store Password in your email. (After Verify)