When you download the copy of Concrete5 those folders are included in the download and should be there when you upload them to your server via FTP, they are not dynamically created.

I am having the same problems. In the Concrete 5 installation page, it comes up with the same message in the "writable files and configuration directories" field, that the above directories are not writeable. And it will not allow me to continue the installation page. I have tried to find the directories but they are not on the paths mentioned. I have tried to chmod some of the directories to 777, but still no luck. So the problem has stalled me.
I don't think the posted reply from Hutman (thanks) has solved the problem for either Neil or myself. (I am on localhost, so no ftp in my case)
Any more ideas?

Create those directories if they don't exist.

The problem I had was the clients hosting had no facility to unzip the install file so I had to do this locally and then upload the files which is when I discovered that certain folders were missing. Even creating these folders didnt work. Eventually I had to upload the zipped install file using ftp and then got the hosting tech support to unzip. Everything then worked. Hope this helps?