How do I get either 0 or a number based on a condition ?

Ok EaglesTony thanks for clarify.

so, can you use this expression and adapt for your case:

let
    // Sample data
    Source = Table.FromRows({
        {"ABC", 123, null},
        {"DEF", 456, "Complete"},
        {"DEF", 999, null},
        {"DEF", 777, "In Progress"}
    }, {"Domain", "AppCode", "TrainingAssigned"}),

    // Group by Domain and count only "Complete"
    Grouped = Table.Group(Source, {"Domain"}, {
        {"TrainingAssignedTotal", 
            each try List.Count(List.Select([TrainingAssigned], (x) => x = "Complete")) otherwise 0, 
            Int64.Type}
    })
in
Grouped

If this response was helpful in any way, I’d gladly accept a 👍much like the joy of seeing a DAX measure work first time without needing another FILTER.

Please mark it as the correct solution. It helps other community members find their way faster (and saves them from another endless loop 🌀.