Speaking after Thursday night's Europa Conference League defeat to FK Qarabag, he said: “The biggest thing is coming somewhere you want to – and playing games.
“This seemed the perfect place for me.
“I was straight up on Thursday. It ended up being a six-and-a-half-hour drive, which wasn’t great, but at least I got here. I got to see the stadium rocking, the fans were unreal and I’m really happy to be here. It was unbelievable. Obviously it was the first time I’d seen the stadium, and the fans were great. Hopefully there’s more of it this season.
“The manager used to play for Newcastle, and I’ve heard great stuff about the club, and the football they play. He’s experienced Newcastle, knows what it’s like, and I’m really looking forward to working with him and his team.”
Longstaff spoke to United team-mate Ryan Fraser, an Aberdonian who started his career at Pittodrie, before joining the club.
“I spoke to Ryan Fraser, who obviously came through the set-up here, and he just said it was a great club and if you get the chance go and play there,” said Longstaff. I didn’t need much persuading other than that.
“What you want as a player is to be playing under pressure and to deal with it. At Newcastle there’s an expectancy to play at a high level. I’m expecting the exact same thing at Aberdeen.
“Whether that’s playing a little further back and getting on the ball, or whether it’s breaking into boxes and scoring goals, I’m happy to do either.
"Like he said, if I can chip in with a few goals, it’s going to be great, so I’m looking forward to it.”
We’ve gathered the best of today’s Premier League speculation below…

. LONDON, ENGLAND - AUGUST 04: The Premier League Nike AerowSculpt strike ball ahead of the Pre Season Friendly match between Chelsea and Tottenham Hotspur at Stamford Bridge on August 04, 2021 in London, England. (Photo by Catherine Ivill/Getty Images)
Premier League Nike AerowSculpt. (Photo by Catherine Ivill/Getty Images) Photo: Catherine Ivill

. Burnley in Roberts talks
Burnley have entered talks to sign Swansea City full-back Connor Roberts. (Sky Sports) (Photo by Koen van Weel - Pool/Getty Images) Photo: Koen van Weel - Pool

1. Burnley in Roberts talks
Burnley have entered talks to sign Swansea City full-back Connor Roberts. (Sky Sports) (Photo by Koen van Weel - Pool/Getty Images) Photo: Koen van Weel - Pool

2. Albion complete Cucurella deal
Brighton have secured the signing of Marc Cucurella after a lengthy pursuit. (Fabrizio Romano) (Photo by ANNE-CHRISTINE POUJOULAT/AFP via Getty Images) Photo: ANNE-CHRISTINE POUJOULAT

3. Brighton linked with Sima
Slavia Prague boss Jindrich Trpisovsky has confirmed that the Czech giants had an agreement with a Premier League club not to play Abdallah Sima on Sunday, amidst Brighton holding talks over a deal for the forward. (O2 TV) (Photo by IAN KINGTON/AFP via Getty Images) Photo: IAN KINGTON

4. Christie in demand
Burnley, Bologna and Stoke City are interested in signing Fulham defender Cyrus Christie. (The Athletic) (Photo by Alex Burstow/Getty Images) Photo: Alex Burstow