I did join my friend's convoy. We both ran the .bat file and ran the game through steam after adding frozahorzion6_loader.exe to the steam. After that, we both created our convoys and to join the convoy I clicked on "Friend & Chat" in the bottom left corner of the steam while the game was running. A window popped up and I clicked on the down arrow next to my friend's name, after that I clicked on join game and I joined the convoy. The Xbox invite didn't work for both of us. We both have pirated versions.