Based on documentation, we should not create new DSA on CA Directory Management UI host. Please refer below
Installing CA Directory Management UI
It says
In case you have production data DSAs which are running on the same machine with the Management UI the you need to separate Management UI from them. How can we uninstall Management UI but not the existing production data DSAs?
Release : 12.6
Component : CA Directory
This procedure will uninstall 12.6 Management UI component only on Windows and leave data DSAs remain (management-ui DSA will be stopped)
1. Please do backup so you can restore the system to the stage before running the procedure below
2. Mount the 12.6 CA Directory Management UI media and run dxmgmtuisetup.exe
3. At "Add and Remove Components" dialog select Modify
4. At "Custom Setup" dialog deselect only Management UI component