Ennis joined Rovers last week on-loan for the season and made his debut in their surprise FA Cup win against Hull City on the weekend.
McCann said: “Hopefully it gives an indication of what we’re trying to do.
“This is a busy window and every time we speak to people they talk about our style of play and how we go about things. They want their players to come here and Manchester United were no different.
“Having a chat with Ethan and Travis (Binnion, Manchester United U21 manager) and showing him around and what we’re about, it just fits with everything that he’s about.
“It shows the progression of this football club that big clubs are now trusting us with their best youngsters. He is certainly one of Man United’s best youngsters. He’s got all the tools to go on and be a top, top Premier League player one day.
“First things first, this is his first loan and we’ve got to give him that platform to go on and show everything that he’s about.
“He makes clever runs, his movement is good - how we like our wide forwards to play. Ethan has got all that.
“I’m really pleased to get him and huge thanks to Man United for trusting us.”