link for high sierra doesn't work, can't find it on app store or itunes or anywhere

I have 10.9.5 Mavericks. I am trying to upgrade to a newer version. I could only download Catalina and it does not install.

https://support.apple.com/en-us/HT208969

Tried above links for mojave, high sierra; they don't work. When I click, it directs me to app store or itunes where I can not find any of them. In my first try it said this item is not available in Turkish store, switch to US store and when I switched it said you can't use US store with this Apple Id. Now it does not ask such questions either, just asks me which app to open(app store or iTunes- non of them opens it)

There was an old version of high sierra, downloaded already, but it said the program is damaged and can't install so I deleted it from apps, restarted several times to download a new one.