If you are trying to convert OLM calendar to CSV file format to manage your data professionally, then you can use OLM Converter from Yota Soft. This tool lets you save all calendar entries to a CSV file without losing a single piece of information.
The software supports all editions of MS Windows such as Win 11, 10, 8, 7, and earlier versions. It also does not need Outlook installation on the machine to start this conversion task. You can download and install it on both 32-bit and 64-bit machines.