Advice on creating a customer portal

Good day all,

I’m needing a little advice. I need to create a site that requires users to sign in and once signed in they need to be able to place orders.

With regard to the private site, the users mustn’t be able to register. My client will create accounts for their customers.

With regard to placing orders, I’d like something that includes a grid that can accommodate an unlimited numbers of rows. Something like a spreadsheet where each row has a combobox that allows the customer to select an item and then specify the quantity required of that item.

I’ve had a quick look at Google Forms but I need something that will alert my client each time an order is placed. I’m not sure that Google Forms can do that.

Hoping for some guidance.

Many thanks

Rob