how to switch platform to android in unity ??

hiii i am new to unity, and i want to switch my platform to android. but, the problem is, when i click the android in build settings, it says “no android module loaded”. and when i click to install with unity hub, it says “the unity version 2019.4.13f1 is already located by the hub. You cannot add modules to a located hub”. how to resolve this issue ?? and i have also tried installing unity installer and when the downloading completes, it says “failed to locate unity.exe”… can someone pls help me with this… I am trying this since past few days, and it has become annoying :(… plssss somebody helpp…

download a version that has LTS in it, they are the most stable versions.