On site https://www.adobe.com/devnet-docs/acrobatetk/tools/ReleaseNotesDC/continuous/dccontinuousfeb2021qfe4... i've found that the 64-bit version of Adobe Reader DC exist and everyone is able to download updates for this version.
Where i can download the Reader DC x64 base? I found link to Acrobat DC x64 https://helpx.adobe.com/acrobat/kb/download-64-bit-installer.html , but this package not contains Reader DC.
After connecting via UK VPN to Reader download site i found that:
After that in Adobe_GDE file i found a direct link to AcroRdrDCx642100120145_en_US.exe. So the tests are in UK, NZ and Australia, but the installing version is en_US. If you change the en_US to another in link, you could change installer to another language. My main question is: What for Adobe is hiding this version?
Nothing is being hidden. The Acrobat product managers decided to roll out the 64-bit Windows version slowly, by geography and/or language support.