You're not technically supposed to "choose a style" in that dialog. The style selector should be prepopulated with the correct style choice for your current map.

If you want to use drawing tools belonging to a different map type than the one you are working in, you need to import the appropriate fill styles first. More about this in this faq topic:

You can't. There is no way for one member to block others seeing what they post. Besides, this being a public forum, people can browse it and look at the images even without an account at all, so banning wouldn't really work even if you could.

For comments, if someone is sending abusive comments or engaging in undesired behavior, you should report them to a moderator. If it was done via private messages, you can add a moderator to that conversation so they can more easily see it themselves.

It is interesting how knowledge disappears from the general hive mind over time. Just about every window has a menu there, it is called the "System Menu", and in the old days, this was also where you closed the program (try double-clicking the icon), the "X" button in the top right is of newer date.

Back in Win3 days it looked like a minus sign, but in Win95 it was replaced with the program icon instead.

The issues are caused by certain program controls not responding correctly to the scaling factor in Windows. It happens when you have it at anything else than 100%. Most of the dialogs should be fixed to work correctly with the scaling, but for any you find that don't work properly, feel free to report them.

Doing a map of that size isn't a problem in CC3+. But it will be a bit time consuming, a map like that is not done in an afternoon.

Since you're mentioning the isometric Schley city set, i am not convinced it will be appropriate for such a large city. I haven't tried, but the isometric sets are generally better when you can see the details a bit more clearly. Might be a good resource for mapping closeup of individual districts for example.

Personally, I am not convinced it is a good starting point doing such a large map if you are unfamiliar with CC3+ though. I recommend starting with something simpler to get some experience first, or it is likely to be overwhelming.

You might want to have a look at this live stream recording where Ralf starts making a small city. Far from the size of your desired city, but shows off the tools and techniques.