Grab OST to PST Converter tool for error-free solution to export OST files to Outlook 2019, 2016. It allows to convert & import OST to Outlook on Windows PC. The tool allows to export multiple OST files into PST format in a single process. The software comes with an demo version too.

Convert OST to PST Manually
Open Outlook and go to the File menu.
Select the Import/Export option.
Choose Export to a file.
Select Outlook Data File (.pst)
Choose whether to export a specific folder or the whole account.
Check the Include subfolders box.
Next, select a destination for the Export, and then click Finish.

Regards,
Peter