I've got the solution for you.
What I did was this:
I moved the spotweb directory out of the openmediavault directory.
I put it in /var/www
Now just alter your apache2 config file, like this:
Apache Configuration
Alias /spotweb /var/www/spotweb
<Directory /var/www/spotweb/>
RewriteEngine on
RewriteCond %{REQUEST_URI} !api/
RewriteRule ^api/?$ index.php?page=newznabapi [QSA,L]
Options Indexes FollowSymLinks Multiviews
AllowOverride None
Order allow,deny
allow from all
</Directory>Save this file as spotweb.conf and place it in /etc/apache2/openmediavault-webgui.d
Restart apache2 and you're done!