The next part of the quotation reads: “I recognized God through revoking the determinations and breaking the intentions. When I determined and I was prevented from achieving my determination and I intended and the fate contradicted my intention, I realized that the administrator was other than me.”
My understanding of this is that sometimes things do not happen in life as we plan or expect, either immediately or long-term. For instance, I may intend to go somewhere, but be stopped by illness, traffic, an unexpected visitor, an unexpected job, etc. I may never intend to go somewhere but be given an unexpected opportunity or gift. (For instance, how some people do not have the resources to perform the hajj but nonetheless are able to do it because someone else facilitates it for them. Some people have the money but are never able to go.) This is true for everyday things as well as long-term things like a university education, a job, a marriage, etc.
Often, when you look back at the big picture, you can see that there was in fact a fate plan, and things did not happen randomly. This is a sort of internal evidence that there is a Planner. Of course, we still have free will and should make our efforts to plan and do our best in things!