How do I host a diagnostic survey on the site?

I'd be grateful for any insights, advice or ideas for further research for this: my client has had a diagnostic tool developed, the typical format where you answer questions and receive a report. That has all been figured out in a clever spreadsheet and I would love to host it on the client's squarespace site but have no idea how - whether it's via plugin or extension, or I hire a developer or what?! Thanks in advance