Input tool for multiple users

Sorry if this is a dumb question,but I've taken over a project at work for a major offer we are running. The project manager has built a tool that has an input where frontline staff enter an ID number and it tells them whether the person associated with that ID has benefited from the offer before.

It's been vetted for data privacy and accuracy, but I'm pretty sure it is unusable. The plan was to upload it to an intranet SharePoint site for use for thousands of frontline users, include it in training.

If I'm not mistaken, I don't believe there is a way to fully lock it down so it can't be edited, and even if you can leaving just one input cell, I'm not sure there are ways to have multiple users use it at the same time without seeing eachothers inputs.

Is there a way in excel to do this?

Thanks