can't access iTunes account

As noted 12.6.5.3 is the minimum version that can access the iTunes store due to changes in encryption requirements. This was an out of sequence release that retains app management features removed from iTunes 12.7. 12.7.2.58 is the next build able to access the store, with 12.8 or better being required for working with iOS 12. Older builds of iTunes can produce an advisory message to upgrade Windows when upgrading iTunes is more appropriate.

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What makes you think you'll lose access to the store by upgrading iTunes to 12.6?

If anything, it's exactly the opposite. I believe that when using Windows, in order to access the iTunes Store, you need at a minimum, iTunes 12.6.5.3. At the time of writing (28th April 2019) the current version for Windows is 12.9.4.102, so why not use that? I can get to the store with it, on my Windows 7 machine.