Craigslist does not allow the inclusion of links from applicant tracking systems in job ads on their site. However, they do allow you to link to a careers page on your own web site (e.g. 'companyname.com/careers'). Workable provides multiple options for building a careers page to link to, whether it’s hosted on Workable or externally.
Alternatively, if you accept resumes from Craigslist via email you can forward those resumes to the job mailbox or manually upload them to Workable.