If you have given him your folder that works on your computer. make sure he has it white-listed on his antivirus and firewall, is running as administrator and has set up permissions like we have said in the rest of this thread then EsDeath is correct. something on his computer is blocking access to the game.
There are no arguments as that is what is happening. you need to make sure that his windows update is correct, that he has the latest /net framework installed correctly too. also if you are playing on windows 8+ try to run the game in compatibility mode for windows XP or windows 7.
as i said before, we tryed all compatibility modes... same error, launched as admin same error, lastest framework, already have, windows 10 totally up to date, i think its something in the computer that block access, but iv tryed everything i know and still dont work... what if its the launcher that its not compatible?? can it happen??