Authorise my iPhone SE 2020 to see it among devices in iTunes for Windows

tl;dr I am using the same Apple account / AppleID on both my iPhone SE 2020 and iTunes for Windows 10. Yet, Windows version of iTunes does not see this iPhone among my devices and "Sync" menu item is disabled. What should I do to fix this problem?

I am using the same Apple ID in both iPhone and iTunes / Windows 10:

I have even authorised my PC within my account (not sure, if that was necessary):

And yet my iPhone is not among my devices. Actually, it seems that I don't have any device, because corresponding menu items are disabled:

As an effect, I cannot see these audiobooks in my iPhone, as they are not being synced up to that device.

What should I do fix this problem and get File > Devices > Sync menu item enabled?

Logging-in to the same Apple account / using the same Apple ID on both iPhone and PC isn't enough to enable sync between these two devices.

In addition, it is also needed to physically connect iPhone to a PC (in this case) for the first time.

Only then iTunes for Windows 10 will:

• recognise device and ask to add it to iTunes library for given Apple ID,
• configure both device and iTunes on PC and
• perform initial data and files sync.

Only after then given mobile device will appear in File > Device menu with its unique name next to Sync in a corresponding menu item.

Some details may be found at Apple Support site in this article.