Allah, in Islamic theology, is indeed defined as the creator of everything. According to Islamic beliefs, Allah is the all-powerful and all-knowing creator of the universe and everything within it.
Regarding space and time, Islamic theology generally asserts that Allah is not bound by the limitations of space and time. As the creator of space and time, Allah is considered transcendent and beyond the confines of the physical universe.
However, describing Allah's existence as "unreal" or "nonexistent" would not align with Islamic beliefs. Muslims view Allah as the ultimate reality, the necessary existence upon which everything else depends. While Allah is beyond human comprehension, Muslims believe in the existence and reality of Allah based on their religious teachings and personal faith.
It is important to note that discussions on the nature and attributes of Allah can vary among different interpretations and understandings within Islamic theology. Islamic scholars and theologians have provided various perspectives on these matters throughout history.