None of the links helped but I found a very helpful YouTube video that solved everything. For some reason, I had to type in this command xcrun /Applications/Xcode.app/Contents/Developer/usr/bin/safari-web-extension-converter path/to/extension instead of the one all the links provide. I tried it and it works. =V5UPRseAhq4 Here is the link to the video if anybody ever stumbles upon this page and needs a solution to the problem.