Admin page displays 404 error

[rolspace.net]

Hi Everyone

I have a problem here. I have built a site with Processwire on localhost and then transferred to my customer's server. a) it's a windows server (unfortunately) and b) there is a domain-mapping for this site, the domain points to a folder of another domain. Sorry, I can't explain it any better, I don't really understand the different types of servers (why do they have to be different anyway...).

My problem is, that I see the main website but not the admin page. Do I have to add anything to my .htaccess file?

I also tried to include web.config file. Not .htaccess nor web.config file have an impact when changing its content. I really have no clue what to do!!

Links: mcconnellacademy.ch, mcconnellacademy.ch/admin

Thanks for any pointing in the right direction!