Installation Issue: Stuck in Allocating Disk Space During Installation (Steam)

Hey i had this same problem but i found a solution. You need to open steam and left top corner press steam then settings and go to downloads and there is clear cache memory, press that during the download when u have that allocating disk space thing open. Then just log in and it should download without any problems, but now i have another problem i can't get the product code because it can't connect to get it...