Create new column with previous ID

hi Omelei 

try to add the column with this:

Custom Previous Opportunity ID 2 = 
VAR _id = [Account ID]
VAR _date = [Startdate]
VAR _table =
FILTER(
    data,
    data[Account ID] = _id
)
VAR _date1=
MAXX(
    FILTER(
        _table,
         data[Startdate]<_date
    ),
    data[Startdate]
)
RETURN
MAXX(
    FILTER(
       _table,
        data[Startdate] = _date1
    ),
    data[Opp ID]
)

it shall work like this: