if you uninstalled InDesign 15.1.3 by installing InDesign 16.4 you did that because of a setting in your Creative Cloud Desktop App. You can change that behavior for future updates and upgrades there.
Now, that the damage is done, you cannot go back to install InDesign 15.1.3 from the CC Desktop App, because Adobe only offers the last two versions of Creative Cloud applications through the Creative Cloud Desktop app: CC 2021 and CC 2022.
You have to talk to the Adobe support to get an installer for InDesign 2020.
The details and some links for this procedure are given here: