Atwa is Zamalek's third signing in the new season after luring Masri's defender Amr Al-Safti and Enppi's full-back Osama Hassan.
He scored Zamalek's first goal in a friendly 2-2 draw with Saudi side Qadesia on Sunday and he left the pitch under crowd ovation.
"I am really happy with my goal that silenced the skeptics who started to criticize me before assessing my performance," he told FilGoal.com.
Atwa said also that he in not worried over competing with Zamalek's talented attacking midfielders for a place in the starting lineup.
"Zamalek have great playmakers like Hazem Emam, Gamal Hamza and (Ghana's Awuley Quay) Junior," he said.
"But competing with such players gives me the chance to improve my game and exert more efforts to secure a regular spot."