The point of a signature is traditionally to demonstrate that a particular person has knowingly and deliberately agreed to a particular set of terms.
In both traditional and digital media, this doesn't have to take any specific form - a simple cross or X has been more than sufficient, even if it has no relationship to the name of the signatory - as long as there is other evidence that it was indeed the claimed party who did sign.
Thus, if you can reliably or reasonably demonstrate that a particular person has agreed to the terms, they can do something as simple as click a button or check a box; typing their own name may be additional security against an accidental click, and a digital signature is that much stronger still.
See this related question on what is needed for proving that the "signer" did indeed "sign".