He didn't give the complete "freeway" directions. Exit the Tropicana via their valet lot (facing Excalibur) onto Las Vegas Blvd. going North. Wait for a big opening because you need to cross all the lanes of traffic to get into the left turn lane at Tropicana Blvd.

Go left (East) on Tropicana heading for the freeway (I15). Get on the I-15 heading South (to Los Angeles). Stay towards the right and look for the 215 exit West. The 215 will take you to the Green Valley Ranch Station Casino, again, you can't miss it, it looms large on your right. Exit the 215 just as you pass the casino.

Have fun!

Jim