Blank CiviCRM Home page after install
Welcome to SE!  Sorry to hear you are having problems installing CiviCRM.
Have you followed the installation instructions here?
Files are created automatically under the templates_c directory. The only thing you need to do there occasionally is to remove all the files.  (Normally that is taken care of by 'clearing the cache').
Is the file owner of the directory the same user as the one running your webserver?
Edit after the question update: yes, you'll need to talk to your hosting company about ModSecurity.