1. Head over to supabase.com and sign up for an account.
2. Once you're in, create a new project from the dashboard.
3. Jot down the project URL and public API key. You'll need these later.

1. Go to the PayPal Developer site.
2. Log in or create a developer account if you don't have one.
3. Set up a new sandbox environment for testing.
4. Grab your PayPal API credentials: Client ID and Secret.

1. In your project directory, run the following command to install the necessary libraries:

   ```bash
   npm install @supabase/supabase-js @paypal/checkout-server-sdk
   ```

2. Make sure to set up your environment variables for security:

   ```txt
   SUPABASE_URL=your_supabase_url
   SUPABASE_KEY=your_supabase_key
   PAYPAL_CLIENT_ID=your_paypal_client_id
   PAYPAL_SECRET=your_paypal_secret
   ```

1. Initialize the Supabase client in your project:

   ```js
   import { createClient } from '@supabase/supabase-js';

   const supabaseUrl = process.env.SUPABASE_URL;
   const supabaseKey = process.env.SUPABASE_KEY;
   const supabase = createClient(supabaseUrl, supabaseKey);
   ```

1. Initialize the PayPal client:

   ```js
   import paypal from '@paypal/checkout-server-sdk';

   const environment = new paypal.core.SandboxEnvironment(process.env.PAYPAL_CLIENT_ID, process.env.PAYPAL_SECRET);
   const client = new paypal.core.PayPalHttpClient(environment);
   ```

1. Create a function to handle the creation of a PayPal order:

   ```js
   async function createOrder() {
   const request = new paypal.orders.OrdersCreateRequest();
   request.prefer("return=representation");
   request.requestBody({
   intent: 'CAPTURE',
   purchase_units: [{
   amount: { currency_code: 'USD', value: '10.00' }
   }]
   });

   try {
   const order = await client.execute(request);
   return order;
   } catch (err) {
   console.error(err);
   return null;
   }
   }
   ```

1. Create a function to capture the payment after approval:

   ```js
   async function capturePayment(orderId) {
   const request = new paypal.orders.OrdersCaptureRequest(orderId);
   request.requestBody({});

   try {
   const capture = await client.execute(request);
   return capture;
   } catch (err) {
   console.error(err);
   return null;
   }
   }
   ```

1. Create a function to save payment details to Supabase:

   ```js
   async function savePaymentDetails(paymentDetails) {
   const { data, error } = await supabase
   .from('payments')
   .insert([{
   order_id: paymentDetails.id,
   amount: paymentDetails.purchase_units[0].amount.value,
   currency: paymentDetails.purchase_units[0].amount.currency_code,
   status: paymentDetails.status
   }]);
   if (error) {
   console.error(error);
   }

   return data;
   }
   ```

1. Use the following code snippet in your frontend to trigger the PayPal payment and handle post-payment tasks:

   ```html

   \`\`\`

This guide offers a step-by-step approach to integrating Supabase with PayPal for payments, ensuring a smooth process across both services.