I don't know if it can be useful but I partially solved it by downloading the files it tells me to be missing.
https://fossies.org/linux/www/ILIAS-6.6.tar.gz/ILIAS-6.6/src/GlobalScreen/Collector/Renderer/ComponentDecoratorTrait.php
https://fossies.org/linux/www/ILIAS-6.6.tar.gz/ILIAS-6.6/src/UI/Component/Button/LoadingAnimationOnClick.php
https://fossies.org/linux/www/legacy/ILIAS-6.5.tar.gz/ILIAS-6.5/src/UI/Implementation/Component/Symbol/Avatar/Avatar.php
I don't understand why it didn't download all the files correctly when we did the git clone, as per the guide.
On the other hand I checked and not even in the tar.gz there are.
Any one can help us ?