NC v15 installation Webdav Error (.well-known redirection )

Hello, i installed debian 9 ( LAMP installation )in a Virtual Machine to eliminate configuration errors in my productive installation ( SSL etc. ). After that i installed Nextcloud 15 into a webserver subdirectory following the guidance :

Apache/PHP version:

dpkg -l | grep apache
ii  apache2                           2.4.25-3+deb9u6                amd64        Apache HTTP Server
ii  apache2-bin                       2.4.25-3+deb9u6                amd64        Apache HTTP Server (modules and other binary files)
ii  apache2-data                      2.4.25-3+deb9u6                all          Apache HTTP Server (common files)
ii  apache2-utils                     2.4.25-3+deb9u6                amd64        Apache HTTP Server (utility programs for web servers)
ii  libapache2-mod-php7.0             7.0.33-0+deb9u1                amd64        server-side, HTML-embedded scripting language (Apache 2 module)

Active apache modules:

 apache2ctl -t -D DUMP_MODULES
 Loaded Modules:
 core_module (static)
 so_module (static)
 watchdog_module (static)
 http_module (static)
 log_config_module (static)
 logio_module (static)
 version_module (static)
 unixd_module (static)
 access_compat_module (shared)
 alias_module (shared)
 auth_basic_module (shared)
 authn_core_module (shared)
 authn_file_module (shared)
 authz_core_module (shared)
 authz_host_module (shared)
 authz_user_module (shared)
 autoindex_module (shared)
 deflate_module (shared)
 dir_module (shared)
 env_module (shared)
 filter_module (shared)
 headers_module (shared)
 mime_module (shared)
 mpm_prefork_module (shared)
 negotiation_module (shared)
 php7_module (shared)
 reqtimeout_module (shared)
 rewrite_module (shared)
 setenvif_module (shared)
 status_module (shared)

MySQL version:

ii  dbconfig-mysql                    2.0.8                          all          dbconfig-common MySQL/MariaDB support
ii  libdbd-mysql-perl                 4.041-2                        amd64        Perl5 database interface to the MariaDB/MySQL database
ii  mysql-common                      5.8+1.0.2                      all          MySQL database common files, e.g. /etc/mysql/my.cnf
rc  mysql-utilities                   1.6.4-1                        all          collection of scripts for managing MySQL servers
ii  php-mysql                         1:7.0+49                       all          MySQL module for PHP [default]
ii  php7.0-mysql                      7.0.33-0+deb9u1                amd64        MySQL module for PHP

Content of /etc/apache2/sites-available/nextcloud.conf :

Alias /nextcloud "/var/www/nextcloud/"

<Directory /var/www/nextcloud/>
  Options +FollowSymlinks
  AllowOverride All

 <IfModule mod_dav.c>
  Dav off

 SetEnv HOME /var/www/nextcloud
 SetEnv HTTP_HOME /var/www/nextcloud


I would like to know where i have to write which strings in which file ( adding or substitute the .well-known entries in /var/www/nextcloud/.htaccess ? ) and which URL i have to use to connect the Cal and CardDav functions to the clients ( thunderbird , gnome, Sailfish OS a.o. )

solution :