Website Directory setup

Hi Guys,
haven’t seen anything specific on this topic - so here goes:

I assume we use 1 main website for all our advertising projects?
If yes, I think we can organise by directory, like
online-projects.com/sas
online-projects.cm/bluetea

If yes, the URL in the advertising then becomes something like:
online-projects.com/sas

Just checking, because I don’t see John add the /test subdirectory in the Google Search Ads.

Thanks for any insights!
WJ