How to add Android 64bit to an existing project ?

Hello,

I just finished to install Delphi Rio 10.3.3 pro and I am trying to add the Android 64bit platform to an existing project but the menu is still grayed (check the the screenshot)

I then read there - http://docwiki.embarcadero.com/RADStudio/Rio/en/10.3_Rio_-_Release_3#Delphi_Android_64-bit_support that :

To preserve your existing installation settings, it is recommended to install 10.3 Rio - Release 3, using the same installer (Offline Installer or Feature Installer) you used when installing 10.3 Rio. To determine which installer you used, verify if the IDE shows the Manage Platforms option under the Tools menu. If the menu item is available it means you used the Feature Installer.

So, I used the offline installer. But I can't figure how to add this platform to the project.

From the menu Tools > Options :