businesscatalyst simply is dead. You must upload to a subfolder on your domain, what one can easily achieve with muse by "publish to ftp". You get asked wether to upload to the main directory or to a folder on server – choose (sub)folder - give it a name (test)
So the test site has the address: www.yourdomain.com/test instead of www.yourdomain.com.
You can publish this now and feel free to choose more yet alternativ subfolders if you want to show