You do not need a driver's license number to file a federal return (so you can leave those fields blank). Only some states required a driver's license or ID number.
Since you are in Florida, it is not needed. Some states may request your driver's license number for state tax returns because they have the ability to match state records and help confirm your identity. This is one more layer of protection against identity thieves.
For more information, you can see the FAQ below:
https://www.irs.gov/individuals/new-security-safeguards