United meet Villarreal in ten days' time in Gdansk.
McTominay said, "It's easy for me to be not so positive after the week we've had but we had three games in five games.
"We're in a situation where we want to finish strongly. Right now we're definitely making progress and the final is a good opportunity for us to put a marker down for next season."
He added: "The will to win at the end is probably the most important win and we have to give everything in our power to win. It's been a tough season but we have to push through it and hopefully get out rewards at the end of it."