* Set up (two words)
* Setup (one word)
Both spellings are correct, but the choice depends on the context.
"Set up" is typically used when describing the action of preparing something or arranging something in a particular way. For example:
* "I need to set up the conference room."
* "She set up a new business."
"Setup" is usually used as a noun to refer to the arrangement or configuration of something. For example:
* "The setup of the room was perfect."
* "The new website has a great setup."
Ultimately, the best way to decide which spelling is correct is to consider the context and the intended meaning.