You will have heard people say, “God is sovereign”. The assumption is that everything that happens is his will, so we must accept it graciously.
I want you to know that “God is sovereign”, but that does not mean that everything that happens is his will.
A soverign God could create angels and sovereignly give them freedom to rebel against their creator.
A sovereign God could sovereignly give authority over the earth he sovereignly created to the people he had created. He could sovereignly decide to give this authority without recourse. He could sovereignly agree that he would not take the authority back from humans if they messed up; even if they gave it to the spiritual powers of evil.
So a situation where the spiritual powers of evil have authority to do evil on earth is consistent with the sovereignty of God.
God is sovereign, but that does not mean that evil cannot happen. He sovereignly created a world, where it could, because he had a greater purpose.