Sam's progressed through the Manchester United Academy system and had loans at Oldham Athletic, Scunthorpe United and Walsall.
He started the 2013/14 season with Manchester United's Under-21 team but went on loan to Yeovil Town in August. That loan spell was cut short due to injury after one game and he returned to Manchester United until January when he joined Doncaster Rovers on loan. Despite Doncaster's relegation from The Championship, Sam's performances were recognised as being outstanding.
In October 2014, having recovered from an elbow injury, Sam rejoined Doncaster Rovers on loan. In early January 2015 the loan was extended until the end of the month but Manchester United recalled him early to allow him to join his home-town team, Preston North End, on loan for the remainder of the season.
With the uncertainty around David de Gea's future, Sam remained at Manchester United at the start of the 2015/16 and was regularly involved with the first team but at best was only ever an unused sub. He returned to Preston North End on loan at the end of 2015 for the remainder of the season.
The 2016/17 season followed a similar pattern to the previous one. Sam remained at Manchester United until January 2017 when he joined Aston Villa on loan for the remainder of the season. He returned to Aston Villa on loan for the 2017/18 season.