Contact Calendar Access Error

Hello,
I have installed a new MIAB with V75.

I try to connect from admin page to :
|Contacts |https://box.example.com/cloud/contacts|
|Calendar |https://box.example.com/cloud/calendar|
but all these two pages shows : Error

Unable to write to the “apps” directory.

This problem is usually resolved by granting the web server write access to the applications directory or by disabling the app store in the configuration file.

As I can learn MIAB install Nexcloud so I think this error comes from that.
My goal is to synchronize my contacts and calendar with MIAB. I used also Davx app for Android to connect and synch contacts and calendar but even with help on admin#sync_guide page my app cannot connect : impossible access the base url is incorrect and service could not be detected. I learn lot of this forum but I cannot find help for this problem.
Thanks