you don't have to sign. some schools just provide the same template for E-version and hardcopy version that's why it is required to sign.
per my knowledge you can just submit and it is considered authorization; or you need to snail mail a signed document to the school, depending on each school's requirement.
But it is indicated in the application form that "please sign electronically", does this mean that I must sign this to guarantee what I fill in above are true?