Problem with px4flow -mission planner 1.3.70

Hi everyone, i am new here:) i have a problem with px4flow. i try to install it on mssion planner 1.3.70 and it didn’t work. then i tried mission planner 1.3.39 and it worked. so my question is: why i can’t use the last mission planner?
Another question, if i would like to use px4 orange, can i use mission planner 1.3.39?