You can easily convert Mac OLM files to .vcf file extension using MacUncle OLM to vCard Converter. The tool supports Mac OS Machines.
Start OLM to vCard Converter Application on Mac OS.
Add OLM file to the software panel using either Add File(s) or Add Folder(s).
Choose vCard from Select Saving Option.
Choose desired Folder from the software panel.
You can also select destination path if required and press the Export button to start the conversion process.
Mac OLM to vCard conversion process completed successfully, you can see the message of completion.