To workspaces with a Web User Interface, the preferred way of logging in is using your institute or EduID credentials, through SRAM.
Time-Based One Time Password (TOTP) is another way which, just as SRAM, enforces Two Factor Authentication.
Workspaces with a Command Line Interface can be accessed via SSH.
Prerequisites
When following along with one of these step-by-step guides, make sure that you have a running workspace (see How to get on board).