1. Just download the all-including 1.93Gb pack linked below, unzip it in your place of preference and run the included 'Total Annihilation Prime-portable.exe'. Keep 'check for updates' disabled and hit start.
2. When you first run the game, you may register on the SpringFightClub server (or login if you already have a SpringRTS account) to play online multiplayer matches. Or you may simply cancel the login process, if all you want is the Single Player mode. To play online, our official servers are *TA Prime - Main Server* and *TA Prime - Test Server*.
3. To play the Single Player mode, make sure the AI opponent is set as 'Scavengers AI', if not you may kick it and/or add a new AI and select Scavengers AI. If you just want a sandbox to test the units and build orders, add a 'Null AI' as your opponent and start the game.
PS: We from the dev team usually play on Wednesdays, 10h30 PM BRT/US Atlantic time, but feel free to arrange any matches you feel like of course. Our Discord server is perfect for that, besides asking any questions and check the development progress of the game. Be our guest!