cant reinsatll

so can you not reinstall on PC with existing files or what? my PC crashed and had to reload windows and I have a drive dedicated to games, however every other drive but my games drive i can install the fm7 to, all drives have enough space and my games drive still has 600gb free, I have permissions over old files however cannot copy them anywhere and i REALLY dont want to reload because at 3MB/s internet speeds that will leave my net down for at LEAST 3.5 days dedicating to a download i shouldn’t have to do again. whats the work around here?

Edit: got it installed on C: drive giving me no room at all left, cant migrate to D: drive due to 0x80070005, i have all permissions over both drives. also no the game cannot stay on c: drive