I have paid for and downloaded Minecraft on my phone and want to download it on my PC (the version run by Microsoft) without paying again. It would be great if you could help.
Pocket Edition (which is avaliable on phones) and Java Edition (which is mainly used on PC) are different games with different features, which are not compatible.
You will have to buy each version (PC, Console, PE) separately.
There is a Windows 10 Edition which is basically PE edition ported on PC, and it is free for Java version owners. But not for other version owners.