I needed to make a suggestion to developer team, but since i don't know where to contact them, i post it here!
Well, ProcessMaker 3.4.x is using PHP 7.3.x and mcrypt extension which was deprecated in previous version (7.2) is now completely removed from PHP (specially i mean Windows Version of PHP)
So, please remove the Mcrypt check for Install Requirements of PM.
I'm not a pro PHP Programmer, but i think openssl is an alternative for mcrypt.
Thanks is advance