Rule with dax

Nihed  I believe you are looking for this, pbix is attached

Column 2 =
IF (
    PPM[Process Steps]
        IN {
        "Open for Competition",
        "Technical Evaluations",
        "Financial Negotiations",
        "Procurement Board",
        "Legal Review",
        "Signature",
        ""
    },
    PPM[Estimated Amount],
    IF ( PPM[Process Steps] IN { "Finalised" }, PPM[Cumulated Contract Amount] )
)

else

Column = SWITCH(TRUE(),
                CONTAINSSTRING(PPM[Steps],"Open for competition")=TRUE()||
                CONTAINSSTRING(PPM[Steps],"Technical Evaluation Stage")=TRUE() ||
                CONTAINSSTRING(PPM[Steps],"Financial Evaluation Stage")=TRUE() ||
                CONTAINSSTRING(PPM[Steps],"Procurement Board")=TRUE() ||
                CONTAINSSTRING(PPM[Steps],"Legal Review")=TRUE() ||
                CONTAINSSTRING(PPM[Steps],"Contract Signature")=TRUE() , PPM[Estimated Amount],
                CONTAINSSTRING(PPM[Steps],"Process Finalized")=TRUE(), PPM[Cumulated Contract Amount])