Could you please provide a detailed explanation of the process for applying for the RRB exam, including the step-by-step procedure that candidates need to follow in order to successfully submit their application? It would be helpful if you could describe the necessary documents required for the application, such as proof of education, identity, and other personal details. Additionally, could you explain the online registration process, including how to fill out the application form, any application fees that need to be paid, and the platforms or websites where candidates can apply? Moreover, it would be great if you could mention any important dates or deadlines that candidates should be aware of, as well as any tips for ensuring that the application is completed correctly and on time.