create table orderline_arrivals 
( 
   orderlineid        number not null, 
   arrival_starttime  date not null check ( mod(to_number(to_char(arrival_starttime, 'MI')), 5) = 0 ), 
   arrival_stoptime   date not null check ( mod(to_number(to_char(arrival_stoptime, 'MI')), 5) = 0 ), 
   article_id         varchar2(10) not null, 
   quantity           number(4, 0) not null check ( quantity > 0 ), 
   check ( trunc(arrival_starttime) = trunc(arrival_stoptime) ), 
   check ( arrival_starttime < arrival_stoptime ), 
   primary key ( orderlineid ) 
) 

insert into orderline_arrivals ( 
   orderlineid, arrival_starttime, arrival_stoptime, article_id, quantity 
) 
select 1, to_date('2021-03-18 08:00', 'YYYY-MM-DD HH24:MI:SS'), to_date('2021-03-18 08:15', 'YYYY-MM-DD HH24:MI:SS'), 'A1', 10 from dual union all 
select 2, to_date('2021-03-18 08:00', 'YYYY-MM-DD HH24:MI:SS'), to_date('2021-03-18 08:15', 'YYYY-MM-DD HH24:MI:SS'), 'A2', 20 from dual union all 
select 3, to_date('2021-03-18 08:10', 'YYYY-MM-DD HH24:MI:SS'), to_date('2021-03-18 08:20', 'YYYY-MM-DD HH24:MI:SS'), 'A1',  5 from dual union all 
select 4, to_date('2021-03-18 08:30', 'YYYY-MM-DD HH24:MI:SS'), to_date('2021-03-18 08:40', 'YYYY-MM-DD HH24:MI:SS'), 'A3', 50 from dual

commit

select 
   to_char(slottime, 'YYYY-MM-DD') as day 
 , to_char(slottime, 'HH24:MI') || '-' || to_char(slottime + interval '5' minute, 'HH24:MI') as slot 
 , article_id 
 , sum(quantity) as quantity 
from ( 
   select 
      s.slottime 
    , case when s.slotno <= a.slots then a.article_id else null end as article_id 
    , case 
         when s.slotno <= mod(a.quantity, a.slots) then trunc(a.quantity / a.slots) + 1 
         when s.slotno <= a.slots                  then trunc(a.quantity / a.slots) 
         else null 
      end as quantity 
   from ( 
      select 
         arrival_starttime 
       , round((arrival_stoptime - arrival_starttime) * (24*60/5)) as slots 
       , nvl(round((lead(arrival_starttime) over ( 
                      partition by trunc(arrival_starttime) 
                      order by arrival_starttime 
                   ) - arrival_starttime) * (24*60/5)), 0) as slots_to_next 
       , article_id 
       , quantity 
      from orderline_arrivals oa 
   ) a 
   cross apply ( 
      select 
         level as slotno 
       , a.arrival_starttime + numtodsinterval(5 * (level-1), 'minute') as slottime 
      from dual 
      connect by level <= greatest(a.slots, a.slots_to_next) 
   ) s 
) 
group by slottime, article_id 
order by slottime, article_id