If your only problem is that the file has the wrong extension, you can change it to .zip by selecting the file and pressing enter. If the file isn't actually a zip file or has been corrupted whilst downloading this isn't going to be any use though.
If your only problem is that the file has the wrong extension, you can change it to .zip by selecting the file and pressing enter. If the file isn't actually a zip file or has been corrupted whilst downloading this isn't going to be any use though.