The most effective way is to use a professional tool like Advik OST to OLM Converter. It converts OST files into OLM format in just a few steps, making them fully compatible with Outlook for Mac.

Steps to Import OST Emails into Outlook Mac:

Download and install Advik OST to OLM Converter.

Launch the tool and add your OST file.

Select the OLM format as the output option.

Choose the destination path and start the conversion.

Open Outlook for Mac and import the converted OLM file.

Learn More: https://www.adviksoft.com/blog/ost-to-olm-converter-import-ost-emails-to-outlook-for-mac/