I also had that error when trying to extract the zipped file. In addition, I took the time to check the sha256 and compare it with the one I had on my computer and they were exactly the same. Therefore, this error is not due to the file being uploaded corrupted or damaged during the upload.
I must also say that to extract the file, I had to calculate where the extract option was in the context menu because instead of going down the menu, it was going up in the Monsta File Manager.