What's the best way to uninstall the LR5?
The Adobe Creative Cloud Cleaner Tool!
It is designed for the task of 'wiping' anything 'Adobe' from a computer system.
CLEANER TOOL LINK
You may find relevent information for the Error Code 213 here (if you understand tech jargon )-
https://helpx.adobe.com/download-install/kb/licensing-errors.html
You should be able to install v5 on the Mac with Sierra, but do not have the Creative Cloud Desktop App installed (wipe it with the Cleaner Tool first). You would only need the Installer.dmg and your Serial Registration Number.
Adobe does not support v5 in any way.
For the Mac with Catalina OS- A subscription to the Photography Plan (20GB) is highly recommended!