Purchased a digital version of a woodworking plan. included instructions that had a link to a free version of sketch up. this should have allowed to both open and modify the zip file. can’t do either. help appreciated
What plan did you get that included a link to download SketchUp?
If I understand correctly, you need to unzip the file to extract the skp file inside. You should then be able to open the skp file with SketchUp Free (in a web browser) or SketchUp Make 2017 (which you will need to download and install).