Assigned user is not assigned to its group

With the following configuration using the scc_resolve module:

## ITK statement
<IfModule mpm_itk_module>        
    SCC_SET_PATH    /bin/bash /tmp/test.sh
</IfModule>

And the following files:

-rw-rw---- 1 zr5094 root      6 21. Apr 11:32 hello1.txt
-rw-rw---- 1 root   zr5094    6 20. Apr 12:40 hello2.txt

I get the following results for the user zr5094:

root@eoan-dev:/# davix-get -H "Authorization: Bearer $(oidc-token egi-p1)" https://webdav-synergy.data.kit.edu/hello1.txt
hello

root@eoan-dev:/# davix-get -H "Authorization: Bearer $(oidc-token egi-p1)" https://webdav-synergy.data.kit.edu/hello2.txt
(Davix::HttpRequest) Error: HTTP 403 : Permission refused 

The privileges are correclty assigned to the user but not for the group id.