@LeeC2202 Thx for all the help. This time it installed properly and gave me the 'mods' folder option. Guess the tool assumes you've already installed mods before. My bad.
Franklin's New Garage mod isn't showing up, though (though I did see the game briefly mention it was loading the 2 garage files). Is it really supposed to be behind Franklin's home?! I mean, his place is a dump!