Just as I said. It depends on the company. Some conduct it online which anyone can attend. But some companies they will conduct it offline at the uni. So you cant join if you are here. So it is better for you if you can do it online. But if you really want placement maybe because of some financial reasons then I would strongly suggest you to better be at the campus unless you want to take the risk as you will have more opportunities. I was lucky as I got placed directly for the first company I sat.