If you don't have a program like WinRAR or 7zip you can select the 'Extract All' option when you right-click the zipped folder, and then selecting 'Extract' in the new window.

Once the zip folder has been downloaded, you'll need to unpack/extract (vel unzip) the folder and it's contents. Some work needs to be done, however, to get this version of tModLoader to work, and this guide aims to support you through the process of downloading, installing and troubleshooting anything you will need support with, else, providing you with the necessary resources and tools you may need. In a solution to some of these issues, there has been a developer working on and creating a 64bit port of tModLoader which overhauls the game and provides a solution to some of the issues faced, while also giving the user more memory to play with, so long as they have the RAM to spare. It's amazing to see that Terraria's unofficial mod 'tModLoader' has finally been officially endorsed and ported over to Steam as it's own little feature, a big Re-Logic seal of approval, however, there are a few things that can limit the experience of users such as the infamous '4GB memory limit' or mods throwing a tantrum which can lead to a browser crash. If you still happen to have any issues that ARE NOT in this guide, please join the Discord found under 'Additional Resources', thank you. We use Steam for many reasons, and trouble shooting personal problems is not one of them that is the Discord's purpose and this guide's purpose. If you have issues, please DO NOT add any authors of this guide or message on their profile page. IF you have an issue read the guide FIRST before making any sort of comment within the Discord server. COMMENTS HAVE BEEN DISABLED!We were getting too many comments about questions that have already been answered for in the guide already or repeated time and time again, or simple fixes that take common knowledge to solve.

Tmodloader installation guide