Some employers ask applicants to fill out an additional application form after filling out initial information on a job board. When you apply through the major job boards like Indeed, SimplyHired, or ZipRecruiter, this additional required application form will be emailed to you.
It often takes several minutes to generate and email the application form. This is not an error. If you get a message after applying that indicates that an additional form is required, you have the option to see if the form has been generated based on the information you gave. If it doesn't, no worries, because again, you will be emailed with a link to complete the form.
In some rare cases, you may not receive the form because you have already applied to the same job at that company (perhaps in a different location) within the past 90 days. If you believe this is the case, please contact the hiring company directly so they can manually send you the form.