Since there is no fourchette for the inner glove, this part is relatively easy.

Start by trimming the inner glove fabric to the right length for the finger. A little longer is fine. You will need seam allowance, and the lining adds bulk. It is easier to undo your work and trim a bit if needed than to make a finger longer.

Tack the end of the plastic tab to the tip of the finger - it won't be visible once you have sewn the glove together.

Use whip-stitch, with a 3mm (1/8") seam allowance to close the ends of the fingers. If you trimmed them with a curve, the inner glove should look reasonably good.