Something that @Takiro and @Someguy may not have considered is that you may be using a very old PC, a PC with a so-called 32-Bit/x86 CPU (CPU = the main processor of your PC), instead of a modern 64-Bit/x64 CPU.
Therefore, your statement may be correct, and you rightly say “Krita 4.4.3 is the latest version”, but it would have been good if you had added the following to your statement: “which can be run on my PC” to make it recognizable as correct from the outset, at least for your, nowadays special case.
Because 4.4.3 is the last x86/32-bit version of Krita that can be executed on such old Windows-PCs.
Therefore, if you want to update Krita to version 5.2.x, your PC must be running one of the modern 64-bit CPUs!³
If you don’t know what kind of processor your PC is running, here are a few tips on how to find out the type of CPU you have.
Please press the key combination Win Key + R², in the dialog that opens enter “msinfo32.exe” and click the OK-Button, then the system type of your CPU will be displayed on the right, in the window that opens, behind "System Type"¹.
In order to be able to install Krita 5.2.2 or the soon-to-be released 5.2.3, it must say "x64-based PC"¹.
Alternatively, press the key combination Win Key + I, select "System"¹ in the window that opens and scroll down the left sidebar to the bottom and click on "Info"¹, then your system type will be displayed on the right behind "System Type"¹ and also what kind of CPU is in your computer.
You can also recognize the CPU type by the name of the CPU, but unfortunately, for marketing reasons, these CPUs are offered under a confusing variety of names for one and the same functionality: x86-64, x64, AMD64, x86_64, or Intel 64, are the names I know.
You can always find the latest version of Krita on the following website:
https://krita.org/en/download/
You say your PC has tons of free disk space, that sounds great and may be true, but it doesn’t contain any tangible information for us. So how many gigabytes of free HDD/SSD space do you have in numbers?
If you could also tell us the size of your RAM, that could be of interest further down the line.
Did you, or someone else for you, possibly install Krita under an administrator account or another user account, and you are now using it with a different user account than when you installed it?
Thank you for your patience!
Michelist
¹Means that it was translated by me from German and may therefore be named slightly differently, as I do not own an English-language Windows. However, the meaning should be similar and correct.
²Win Key = the Windows key on your keyboard. Sometimes it is the Windows symbol printed on that key, sometimes the abbreviation Win is printed on it, and very seldom Windows is written out in full.
³You would need to upgrade your hardware (maybe more expensive than replacing it with the following), or alternatively buy a new or used PC with a x64 CPU, on which you could then install a 64-bit Windows and an up-to-date Krita.