I am not one of the researchers, but I will give you my take on what they are trying to do. They are attempting to find protein fragments which will exactly fit various binding sites on the virus. The point of that is with the binding site locked up, this will be an inhibiting factor in the ability of the virus to replicate or propagate. There are literally many millions (or more) ways to get the millions of protein samples to possibly bind when and where they would do the most good. Then even when they get a good binding candidate there are a multitude of other questions which need to be answered such as how to synthesize the protein, is it toxic, etc. A long and laborious process of which this basic research is only the beginning. Perhaps someone else can explain it better.
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