Try this,

SELECT Acc.Account,Fct.ORGANIZATION ,Fct .Year,Period,

CASE WHEN Acc .[SIGN]='Cr' THEN SUM(Fct.AMOUNT ) ELSE 0 END AS Cr,

CASE WHEN Acc.[SIGN]='Dr' THEN SUM(Fct.AMOUNT ) ELSE 0 END AS Dr

FROM #ACCOUNT Acc

INNER JOIN #FACT Fct ON Acc.ACCOUNT=Fct.ACCOUNT

GROUP BY Acc.Account,Fct.ORGANIZATION,Fct.Year,Period,Acc .[SIGN]