Yes. digitalOcean provides virtual private servers. So you could set up hundreds of users and let them all login if you really wanted to.
I would suggest using ssh keypairs for login authentication instead of passwords, more secure.. be sure to disallow root login, and only give very trusted people with some server management experience sudo access.
If you don't know what any of that means, you need to buy yourself a book or two on basic linux server management.. that is a very important skill to have.