How do I code a custom bulk order form?

Hello,

I have decent html, css, and liquid knowledge, but am not sure how to approach the below project. I am looking for any insight and direction on what to start figuring out. I would love to teach myself any skills I am lacking.

The project is to build a custom bulk order form. The general idea is to work like this FMW Fasteners form. I see theirs is built at the collection level, but I do not need that. Product variants would suffice.

Any direction is appreciated, even if it is just, “learn xyz and this will all makes sense.”

Thank you!