"You won't have access to manage apps", posted fixes don't work

[pault918356]

New-to-me Mac, running Catalina. Main machine before ran High Sierra. Have kept the old machine, so running two copies of CS, which should work I believe. All files were loaded onto new machine via Time Machine. 

Read the posts about editing serviceconfig; don't have that file on Catalina. 
Read the post quitting, signing out then  re-naming opm.db. Tried that, same message. 
Saw the posts about uninstalling; used the Uninstaller Cleaner tool, reinstalled, same message. 
Tried the combination of 3 and 2, uninstalling, renaming opm.db then reinstalling, same message. 

InDesign 15 is still working, but I need to install 16 for compatibility with colleagues.... urgently! 

Any ideas please? 

[pault918356]

Should've mentioned, single user, my licence. 

[pault918356 · Accepted solution]

So, it took a long time, maybe an hour with Adobe Remote Support to sort this. 

Cleared lots of files twice over. Apparently the issue was as system configuration problem, the configuration files were not having access to the CCDA application. 

So - a shout-out for Arvind, the remote support agent, for patience and expertise. Thank you, Arvind.