Flight Instructor reported their student was the cause of a NMAC while in the traffic pattern during the student's solo flight.

Narrative

My student almost caused a mid air collision during his solo. On my day off; the flight the flight school had him solo. I have not flown with the student in about three weeks. Being a 141 school I was trusting the standards to still ensure his competency. He was given the green light by another instructor at the school. Not being there I still elected to go over the details of the flight with the student. I discovered the incident by a phone call from my student upon landing and then again hours later from the flight school. ATC instructed him to follow traffic left in the crosswind. He failed to identify the correct traffic thinking the traffic abeam his wing in the left downwind was the traffic to follow. He turned left crosswind which resulted in cutting off another aircraft causing them to make evasive maneuvers. ATC had my student continue south and then rejoin and continue his landing practice. Upon landing; he stated he failed to look at any ADS-B in traffic. The student was confused how he did not know it was a problem until hours later. The student was experiencing some external pressure that may have resulted in this incident. The student wants to get through training at a timely pace which has not been happening. The students total wind limitation was 7kts. After listening to the ATC recordings I discovered that before taking off for his lap in the pattern; there was a wind report of 8 gusting 13 kts. Being that this happened towards the end of his 3.1 hour flight; the student might have not realized the fatigue he was enduring operating outside his limitations. This might have caused him to neglect looking at his ADS-B in. When discovered and asked the student why he continued it was due to wanting to get the mission done.