Career fairs have two purposes: For the company it's a way to establish / further their brand, and for students it's a way to get their resumes to companies and talk to employees.
As someone who has been to a lot of career fairs to represent my company, it's really tedious to hear hundreds of students describe their course projects with a lot of sincerity.
If you are interested in chatting with an employee, please do so and I will be happy to talk about my experiences. This is the biggest value of a career fair for students, coz they can submit resumes on online portals anyway.
Otherwise just submit your resume and get going. This whole facade of pretending to care about the company and going on and on about having done this project and that project is very very pointless.