The Install Wizard will need to be able to copy files and write them to the root of the site.
if the permissions at the root of the site cannot be changed to allow write access, you will need to perform the install on the local server. After the install completes, edit the connection/powercmsconnection.php file with the correct details for connecting to the remote database server. then upload it to the remote server. after uploading all of the files, export the database tables created by the install on the local server and import to the remote MySQL Server