We do require a CV (resume) in PDF format. Otherwise, your profile will not be attractive to any startup. Because it will be empty.
The better your CV, the more it shows how serious you take your job hunting efforts. There are multiple online services helping you to create your CV. One good tool is Standard Resume, for example, but there are others as well!
If you want to use the LinkedIn feature to save your LinkedIn profile as a PDF, be sure to doublecheck that the PDF does not have typography errors - with many characters the conversion to a PDF does not work properly.