Hello Ricardo_Santos,
I have follow this wiki: https://github.com/nextcloud/cms_pico/wiki/Admin-Settings#customizing
I have seen your issue Apache configuration difficulty #39
for apache i have just add this line to my site.conf in /etc/apache2/sites-available:
RewriteRule /sites/(.*) https://your.domaine/index.php/apps/cms_pico/pico/$1 [QSA,L]
And restart your apache service