If I understand you correctly, you need to create a 7-tuplet, right?

What version of Finale are you using? - perhaps v26?

Windows or Mac?

Are you using the Simple Entry Tool or the Speedy Entry Tool?

Both entry tools have a Tuplet (sub-)Tool (= no need to switch to the Tuplet Tool on the Main Tool Palette).

In the Simple Entry Tool you can create a 7-tuplet like this:

Enter the first note.

Hold down the Alt key, and hit the number 9 key. Finale opens the Simple Entry Tuplet Definition.

Define your tuplet (e. g. 7 Eighths in the space of 2 Dotted Quarters). Click OK.

Enter the remaining six notes.

I posted an illustration on the OP's duplicate post with a summary of the Speedy method.

As did I. Looks like we all woke up at the same time!