Just for completeness in case someone runs across this. Yes, there is some ambiguity in Windows 10. I found the ACP Config directory. It does not go in documents of the current USER. Instead and it goes to the place indicated in the picture below:


However, path is an alias and the literal path (typing from the command prompt for example) is C:\USERS\Public\Documents\ACP Config
The ACP Astronomy directory still goes under the USER's documents.

I hope this helps someone else.