Current DO280 for OpenShift 4.5 does not use nor need the ocp4.config, and has not needed for a many months already. This was required by a somewhat older version of the course, targeting OpenShift 4.2, that required a different classroom architecture. That old version was retired and there's no way you can reach its classroom environment.
If you meant one of the courses using shared clusters, such as DO180 and DO288, and DO280 was a typo, that file is created by students performing the first guided exercise from the course, that runs lab-configure to create the ocp4.config file. If you rebuild your classroom (as in delete and re-create) you have to perform that first exercise again.
Actually if you try any "lab exercise start" it should warn you that you need to go back to the exercise that runs lab-configure.
