After fighting back from 2-0 down to draw 2-2 at Blundell Park, United were eliminated on penalties on Wednesday night by the League One team.
Afterwards, Artell said: "This is an accumulation of 15 months, 18 months, all encompassed in one night. Look, they’re an unbelievable team, Manchester United.
“They’ve got an unbelievable manager (Ruben Amorim) and they’re on the right track, you can see that.
“We’ve got an unbelievable group of players as well, who want to play for this football club, live in the area and want to get better every day.”
Artell also stated: “The lads were terrific. They deserve every plaudit, every credit and accolade that will come their way.
“It’s one we’ve been working towards for a long time – to put this club back on the map.
“I appreciate it’s one night. There’s a long way to go, we’ve just started off the league – we’re unbeaten this season – and nights like this don’t come around very often.”