In the article below, you'll find information on the two ways you can activate automatic check-in for your users.
1- Auto-clock when you create a new shift
It is possible to Auto-clock a specific shift by clicking the auto-clock checkbox when you create a new shift.
A good use for this option would be for an employee training when you don't want him to clock in/out.
Note: This feature is only available to organizations with the Time & Attendance add-on module.
2- Automatic time and attendance via employee profile
It is also possible to activate automatic clocking to an employee's profile for all his or her shifts via "HR" -> "Employees" and the "Settings" profile sub-section. Here's how to do it:
If your employee's clockings doesn't seem to be transferring his or her timesheet correctly, here's an article that might shed some light on the subject.