how am i not in ucl?

ok don’t ask how but last season i got to 4th with brentford and i look in the ucl table to see who we play but for whatever reason we’re in the europa league???? i thought top 4 got ucl in the prem, i had the offer to join athletico madrid to play ucl but i decided to stay at brentford because i thought id play ucl football and i could do something magic with brentford like ajax that one season in ucl.

some1 pls help me