Complex sentence: United opted not to sign him after he appeared in five games that season but after a brief trial with Doncaster Rovers Thickett was offered professional terms at nearby Rotherham Town where he became a regular in the first team and appeared in The Football League.
Split into simpler sentences: United opted not to sign him after he appeared in five games that season. After this, he was offered professional terms at nearby Rotherham Town where he became a regular in the first team and appeared in The Football League.