Can't choose my Dropbox folder and cannot see the advanced settings after reinstall

Hi Hannah, 

The current status is Dropbox fully uninstalled. Here a detailed sum up of the situation: 

Clean reinstall attempts failed

I tried multiple complete clean reinstalls:

Using the offline installer 237.4.5655
Using the online installer
Removing all Dropbox folders in AppData (Local and Roaming) and other leftover files between attempts
Testing under both Windows accounts:
Power User (my usual account)
Administrator
Testing with and without admin elevation

Problem:
During every reinstall, I never get access to the Advanced option that allows choosing an existing folder location (C:\Dropbox).
Dropbox never reaches the “Pick your Dropbox folder” screen. It goes directly into a sync state or a setup loop. 

Note: 
The only discrepancy I notice about the reinstall process when reading the "How to run an advanced reinstall" article is that at steps 8 to 10 I deleted all the complete "Dropbox" folders (not just "Client" folders) from  %APPDATA%, %LOCADATA%, ETC. between clean reinstalls. 

Current status

Dropbox is fully uninstalled at the moment. There appear to be no trace of Dropbox app on my computer. 

I need help restoring:

The ability to select my existing C:\Dropbox folder during setup
Correct local/cloud file states
Reliable selective sync behavior
A way to reverse the unexpected forced changes made by the update

I have spent two entire days trying to recover from this situation. 

Thanks for your help. 

PS. I contacted support but Chat crashed two times on my and email support only referred to the above mentioned "advanced-reinstall" article