What does your tag cannot-download mean? You got an installation information message, hence you must have successfully downloaded the installation package.
Just a hint: Download KB2919355 from Download Windows 8.1 Update (KB2919355) from Official Microsoft Download Center manually (select your operating system’s language accordingly), try to install manually and if it is already installed, you’ll get a respective message (and don’t forget to reboot your system).
Microsoft ended mainstream support for Windows 8.1 on January 9, 2018, and extended support will have ended by January 10, 2023.
Microsoft Help: Windows 8.1 Update 1 (KB 2919355) - reinstall updates that are already on a machine?:
The conclusion from that link is that your machine is NOT updated, and you need to install the April 2014 update. Good advice from @opaque on how-to install it.
Edit: Daft mistake: copied the wrong MS link & did not check it afterwards. Now fixed (thanks to @mike-kaganski for the heads-up).
(My system: LO Version: 5.2.7.2 under Devuan Linux 2.1 (ascii))
If this helps then please tick the answer (
)
…and/or show you like it with an uptick (∧)
@AlexKemp: please pay attention to the details.
The link you gave (on MS support site) is unrelated to KB2919355 - it’s about upgrading Windows 8.0 to 8.1; OP already has 8.1.
It’s totally unclear what in the question could be tested using LO 5.2.7.2 (given that OP wants to install 6.4.5.2), or using Devuan Linux (given that OP asks about Windows). The last remark about “or install Linux” does not justify that (and there’s an older version of LO - namely, 5.4 - that will run without the update on OP’s Windows 8.1 without the April roll-up).