Set Field length for Custom Field created via Application Composer in HR Helpdesk

We have created a custom field on the 'Create Helpdesk Request' page to capture Employee ID using Application Composer. It is a 'Number' field. We want to restrict the number of characters to 7 with no comma separators. As seen below, the maximum length has been set to 7. Despite this, when the employee enters the Employee ID, it is allowing more than 7 numbers in the field. It is also adding the comma separators. How can we restrict to just 7 characters with no comma separators?