It is about this line:

MAX ( (sysdate + (RE_ENTRY_TIM - EXIT_TIM)*24*60*60 - sysdate) ) INTO HRESP_MX, 
                                                                 ---- 
                                                 remove INTO here, use AS

INTO clause is used in PL/SQL, while you’re using pure SQL.

Furthermore, if I’m not wrong, you could/should remove both SYSDATE calls as you’re basically

sysdate + something - sysdate 

which leaves something only, i.e. it becomes

MAX ((RE_ENTRY_TIM - EXIT_TIM) * 24*60*60) AS HRESP_MX, 

As you’re using an aggregate function, it means that all non-aggregated columns/expressions should be part of the group by clause, which means that the whole case expression should be moved in there.

What is dat_tim column’s datatype? It is it a DATE (should be), then don’t compare it to a string. Apply to_date function with appropriate format mask.

No:

DAT_TIM BETWEEN '05/09/2024 05:11:00' AND '05/09/2024 05:58:59'

Yes:

DAT_TIM BETWEEN to_date('05/09/2024 05:11:00', 'dd/mm/yyyy hh24:mi:ss') 
            AND to_date('05/09/2024 05:58:59', 'dd/mm/yyyy hh24:mi:ss') 

Finally, I don’t know about your database, but in mine numbers have decimal point, not comma, so maybe this

CASE WHEN ( HRESP_MX BETWEEN 0,000 and 0,200  ) THEN  'R-02'  -- comma

should become

CASE WHEN ( HRESP_MX BETWEEN 0.000 and 0.200  ) THEN  'R-02'  -- point

If that’s not the case in your environment, disregard this objection.

• Decimal Points should be . not ,.
• You cannot use HRESP_MX in the CASE expression when you’ve declared it in the same SELECT clause; instead use the calculation that underlies the alias.
• INTO should be AS.
• Don’t ORDER BY a date string with the format DD-MM-YYYY, instead, ORDER BY the underlying time.
• Don’t compare dates to strings. Oracle will try an be helpful and perform an implicit string-to-date conversion but it will not work be guaranteed to work (especially if you have users in different territories around the world).

and

• If you are finding the MAX(something) then you probably do not also want to GROUP BY something at the same time.

Something like this:

SELECT TO_CHAR( date_hour, 'DD-MM-YYYY'      ) AS DATET,
       TO_CHAR( date_hour, 'DD-MM-YYYY HH24' ) AS TIMET, 
       CRD_FIID,
       MAX(hresp) AS hresp_mx,
       CASE
       WHEN MAX(hresp) BETWEEN 0.000 and 0.200 THEN  'R-02'
       WHEN MAX(hresp) BETWEEN 0.201 and 0.300 THEN  'R0.2'
       WHEN MAX(hresp) BETWEEN 0.301 and 0.400 THEN  'R0.3'
       WHEN MAX(hresp) BETWEEN 0.401 and 0.500 THEN  'R0.4'
       WHEN MAX(hresp) BETWEEN 0.501 and 1.000 THEN  'R0.0'
       WHEN MAX(hresp) BETWEEN 1.001 and 1.500 THEN  'R1.0'
       WHEN MAX(hresp) BETWEEN 1.501 and 2.000 THEN  'R1.5'
       WHEN MAX(hresp) BETWEEN 2.001 and 2.500 THEN  'R2.0'
       WHEN MAX(hresp) BETWEEN 2.501 and 3.000 THEN  'R2.5'
       WHEN MAX(hresp) BETWEEN 3.001 and 3.500 THEN  'R3.0'
       WHEN MAX(hresp) BETWEEN 3.501 and 4.000 THEN  'R3.5'
       WHEN MAX(hresp) BETWEEN 4.001 and 4.000 THEN  'R4.0'
       WHEN MAX(hresp) BETWEEN 4.501 and 5.500 THEN  'R4.5'
                                               ELSE  'R5.0'
       END AS r_value
FROM   (
  SELECT TRUNC(entry_tim, 'HH24') AS date_hour,
         CRD_FIID,
         (RE_ENTRY_TIM - EXIT_TIM)*24*60*60 AS HRESP
  FROM   ORACLE.File_r6        
  WHERE DAT_TIM BETWEEN DATE '2024-09-05' + INTERVAL '05:11:00' HOUR TO SECOND
                    AND DATE '2024-09-05' + INTERVAL '05:58:59' HOUR TO SECOND
  AND   Resp_Cde     <> '206'
  AND   TYP          IN ( '0210', '0220' )
  AND   RESPONDER    = '5'
  AND   TRAN_CDE_TC  <> '50'
)
GROUP BY
       date_hour, 
       CRD_FIID
ORDER by
       date_hour,
       CRD_FIID;