issues with first 6.0 beta setup via composer

[Barbers]

Hello everyone and thank you for starting with Horde 6.

I tried to install Horde 6 via composer and failed.
I hope this ticket will help you.

I got a fresh ubuntu 24.04 on a hetzner vm.
It ships with php 8.3 .

apt install certbot libapache2-mod-php python3-certbot-apache unzip
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('sha384', 'composer-setup.php') === 'dac665fdc30fdd8ec78b38b9800061b4150413ff2e3b6f88543c636f7cd84f6db9189d43a81e5503cda447da73c7e5b6') { echo 'Installer verified'.PHP_EOL; } else { echo 'Installer corrupt'.PHP_EOL; unlink('composer-setup.php'); exit(1); }"
php composer-setup.php
php -r "unlink('composer-setup.php');"
mv composer.phar /usr/local/bin/composer
cd /var/www/html
wget https://github.com/horde/base/archive/refs/tags/v6.0.0beta1.zip
unzip v6.0.0beta1.zip
cd base-6.0.0beta1
cp -r * ../
cd /var
chown -R www-data:www-data www
cd /var/www/html
sudo -u www-data composer install

This ends up with some errors. Excluding dependencies I think these are helpfull.

Composer could not detect the root package (horde/horde) version, defaulting to '1.0.0'. See https://getcomposer.org/root-version
- Root composer.json requires horde/alarm ^3 || dev-FRAMEWORK_6_0 -> satisfiable by horde/alarm[dev-FRAMEWORK_6_0, 3.0.0alpha1, ..., v3.0.0alpha5].
- horde/alarm[3.0.0alpha1, ..., v3.0.0alpha3] require php ^7 -> your php version (8.3.6) does not satisfy that requirement.
- horde/alarm[dev-FRAMEWORK_6_0, v3.0.0alpha4] require horde/translation ^3 || dev-FRAMEWORK_6_0 -> found horde/translation[dev-FRAMEWORK_6_0, 3.0.0alpha1, v3.0.0alpha2] but it does not match your minimum-stability.
- horde/alarm v3.0.0alpha5 requires horde/translation ^3 -> found horde/translation[3.0.0alpha1, v3.0.0alpha2] but it does not match your minimum-stability.

Now the composer.json wants "php": "^8.2", but the dependencies only support php 7 .
I think the dependencies are still aplha and not in beta.
So I'm adding '"minimum-stability": "alpha",' and switched to php 7 as requirement in the composer.json .
Of course I also need to switch to php 7.4 and try again.

apt remove libapache2-mod-php
apt autoremove
add-apt-repository ppa:ondrej/php
apt install libapache2-mod-php7.4 php7.4-curl php7.4-mbstring php7.4-xml
sudo -u www-data composer install

This ends up with the following line in the error.log:

PHP Warning: require_once(Horde/Autoloader/Default.php): failed to open stream: No such file or directory in /var/www/html/lib/core.php on line 44