Check your spam and junk folders, as well as any inbox filters (such as the Gmail "Updates" folder), just in case the confirmation email ended up there.
If you may have accidentally mistyped your email while filling out the application form, try re-applying, making sure the email address you provide is valid. The employer will need it to contact you.
Please note that if you had applied to the same position in that company previously and the employer has already reviewed your profile, then your application will be considered duplicate. In this case, you will not receive a confirmation email from Workable.