iTunes 12.6.5.3 is approximately eight years old and apart from anything else it no longer allows access to the iTunes Store. It's not clear why that version would be recommended now, but if you have created your library or made any changes to it since 2018, that will be why that old version cannot read it.
The version of iTunes I'm using (12.13.11.1, which is the latest version on the day of writing) does let you import your own music (i.e. music that you created or obtained from a digital music store (such as Amazon and Bandcamp for example). However, Apple has been encouraging people to use the newer apps that they hope will replace iTunes, but effectively at this time, those apps do not let you use your own library of music.
To sort this out, you will need to install the latest version of iTunes, either from the Microsoft Store or directly from Apple and then follow the steps below. The Apple download, which is very slightly different to the version in the Microsoft Store, should be available from iTunes - Apple. I use the download from Apple. Note that the last time I checked, the Microsoft Store version updates automatically and does not show you which version is installed. The Apple version does, which makes it much easier to confirm which version you have installed:

On the download iTunes page, shown below:

you will notice the Get it from Microsoft button. But if you scroll down the page you will see (in very small print) Looking for other versions? Mac OS > Windows >. Choosing the Windows option takes you to the download page. (I cannot link to it directly.):

Once installed, make sure that the Apple TV, Apple Music and Apple Devices apps are not installed. If they are, you will need to uninstall them in order to make your library visible. In addition, the Apple Music (subscription service) (why anyone would give two different products the exact same name is a mystery to me) will also prevent you from using your own library. If you have subscribed to Apple Music (even just for the trial period) you will need to end it.