Oracle – ORA-29913: error in executing ODCIEXTTABLEOPEN callout when inserting csv into oracle

I'm trying to execute this code in PL/SQL:

create or replace directory ext_tab_dir as 'C:/mydir';
GRANT READ,WRITE ON DIRECTORY ext_tab_dir TO PUBLIC;
DROP TABLE emp_load;
CREATE TABLE emp_load (v1 VARCHAR2(4000), 
                        v2 VARCHAR2(4000) 
                        )
   ORGANIZATION EXTERNAL (
     TYPE ORACLE_LOADER DEFAULT DIRECTORY ext_tab_dir
     ACCESS PARAMETERS (
     RECORDS DELIMITED BY NEWLINE
     BADFILE ext_tab_dir:'bad.bad'
     LOGFILE ext_tab_dir:'log.log'
     FIELDS TERMINATED BY ','         
     )
     LOCATION ('testfile.csv')
   ); 
--   INSERT INTO tablename(v1,v2)
   SELECT * From emp_load    

and then getting next errors:

ORA-29913: error in executing ODCIEXTTABLEOPEN callout    
ORA-29400: data cartridge error error opening file C:/mydir/log.log

I do get that it has to do something with permissions, but I'm the one who created that directory, so how do I grant priveleges to myself if it is set like this by default? Is there any way to perform that sort of operation from PL/SQL?