/etc/freeradius/3.0/mods-config/sql/counter/ is in freeradius-config 3.0.12+dfsg-5+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/etc/freeradius/3.0/mods-config/sql/counter/mysql/
/etc/freeradius/3.0/mods-config/sql/counter/mysql/dailycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/mysql/expire_on_login.conf
/etc/freeradius/3.0/mods-config/sql/counter/mysql/monthlycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/mysql/noresetcounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/postgresql/
/etc/freeradius/3.0/mods-config/sql/counter/postgresql/dailycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/postgresql/expire_on_login.conf
/etc/freeradius/3.0/mods-config/sql/counter/postgresql/monthlycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/postgresql/noresetcounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/sqlite/
/etc/freeradius/3.0/mods-config/sql/counter/sqlite/dailycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/sqlite/expire_on_login.conf
/etc/freeradius/3.0/mods-config/sql/counter/sqlite/monthlycounter.conf
/etc/freeradius/3.0/mods-config/sql/counter/sqlite/noresetcounter.conf