Creating security label in Postgresql 9.5 returns provider not loaded error

Hi, I'm installing postgresql anonymizer in my 9.5 local cluster using the steps provided in:

• https://postgresql-anonymizer.readthedocs.io/en/latest/INSTALL/
• https://postgresql-anonymizer.readthedocs.io/en/latest/NOTES/#support-for-postgresql-95
• #20 (closed)

While the installation process didn't returned no errors when I try to create a security label on skynet's role I get the following error:

postgres=# SECURITY LABEL FOR anon ON ROLE skynet IS 'MASKED';
ERROR:  security label provider "anon" is not loaded

Recreating the pg_config table also didn't solve the problem;

postgres=# create extension anon;
ERROR:  extension "anon" already exists
postgres=# CREATE TEMPORARY TABLE pg_config AS SELECT 'SHAREDIR'::TEXT AS name, '/usr/share/postgresql/9.5'::TEXT AS setting;
SELECT 1
postgres=# select anon.load();
WARNING:  The path '/usr/share/postgresql/9.5/extension/anon/' does not exist. Data is not loaded.
 load 
------
 t
(1 row)

postgres=# SECURITY LABEL FOR anon ON ROLE skynet IS 'MASKED';
ERROR:  security label provider "anon" is not loaded

Am I missing a important step or something like it? Thanks.