If you select PST as your output option, then it will show you this screen:
From the same screen you can also select option that is Separate PST per MBOX.
Now, you can utilize the filtration options.
Filters by Date – In this option, you can set filters according to date by selecting specific date-range in “From” and “To” date field for achieving selecting MBOX emails conversion.
Now, hit on Browse option and choose saving path to save resultant files where you want.
After selecting destination location, press on Convert button to initiate the conversion procedure of MBOX files to another format. You can view live conversion during the process.
Once the whole conversion is finished, a pop-up window will appear showing the message like Conversion is Done. Then, press on the OK button to accomplish the process.
After clicking on OK option, the software will enable View Log option.
The software will open the same log report.
Navigate to the folder location of your resultant files and click on the folder to open and access the resultant files
Now open PST files in Outlook by clicking on File >> Open & Export >> Open Outlook Data File. Select the PST file and click OK button.