In the product's form view, tick 'Can be sold' boolean.

To give a portal access to the customer, go to that customer and click on 'Grant portal access' from the action button.

Click on the 'Grant access' in portal access management wizard.

Go to the portal => request product.

Press the 'Add Product' button to add the products.

It shows an alert if you have not selected any product and you try to send the request.

Select products with product quantity and enter invoice & shipping address, you can delete selected products from the delete smart button.

After selecting a products, click on the 'Send request' button.

It shows a success notification after successfully send the request.

The quotation backend view.

Go to the portal => quotation.

Go to the quotation => list of the quotations.