Unable to install 1.15.2 (outdated) Java client version to play with a 1.15.2 world

Hello, I'm unable to connect to a 1.15.2 server with updated (1.16) Java client (server outdated).

I tried to install the 1.15.2 version as per  https://help.minecraft.net/hc/en-us/articles/360034754852-Changing-game-versions-

But the dropdown that is supposed to show available versions stays empty.