ORA-01950 error during the execution of insert statement
This is already asked on ORA-01950: no privileges on tablespace 'USERS' [closed]. It was answered as:

You cannot insert data because you have a quota of 0 on the tablespace. To fix this, run 

ALTER USER &lt;user&gt; quota unlimited on &lt;tablespace name&gt;;


or

ALTER USER &lt;user&gt; quota 100M on &lt;tablespace name&gt;;


as a DBA user (depending on how much space you need / want to grant).