From my experience, if you have a lot of VCF (vCard) files and want to add them to Microsoft Outlook at once, the best way is to use a tool that offers batch conversion.

I have personally used Softaken VCF to PST Converter for this kind of requirement and found the tool quite easy and reliable. With this, you can select all the VCF files at once and convert them into a single PST file, which can be imported directly into Outlook. All contact information like name, mobile number, email, address, etc., comes without any error.

This software runs on almost all Windows versions (like Windows 11, 10, 8.1, 8, 7, etc.) and supports all Outlook versions (from 2021 to 2003). Another good thing is that it also has a free trial version, so you can test it first to see if it is right for you or not.