Hope you are doing well.
Method 1 :
Please follow the steps given below.
Step 1 : Go to EdurekaVM.ova file and Open with Oracle virtualbox
Step 2 : Click on import
If the method 1 is not working try the Method 2
Method 2 :
Please uninstall the virtualbox 5.x version, download and install virtualbox from below link and try to import the VM
Please let me know if you have any further issue regarding this query