RT 5.0.5 does not start (nginx server)

RT web interface does not start, there are some file permission problems…
during install when i run “fixperm” this is being set:

# Make the web ui's data dir writable
chmod 0770      /opt/rt5/var/mason_data \
chown -R www-data       /opt/rt5/var/mason_data \
chgrp -R www-data       /opt/rt5/var/mason_data \

when I try to run it after install i gettind error:

( sudo journalctl --unit rt-server.\* )
mailer RT[8515]: [8515] Cannot create directory '/opt/rt5/var/mason_data/obj' (mkdir /opt/rt5/var/m>
                                 ) for user 'rt', group 'rt'. Perhaps you need to create or set permissions on your>

It seems like the RT web interface is experiencing issues starting up due to permission problems related to the mason_data and session_data directories. The error message indicates that the application is trying to create a directory under /opt/rt5/var/mason_data/obj but is failing because the permissions or ownership settings are not correct for the user rt and group rt.

Looks like the mason_data and session_data directories are owned by the user and group www-data. (what is in line with “fixperm” command) However, the error message suggests that RT is attempting to operate under the user rt and group rt, which do not have the necessary permissions.

I do not have any experience with RT, I would like to mess the installation up…
What should be done?

Is RT supposed to run as the user rt and group rt, or as www-data?