Download:
Download is the install file, from there the single files for your use are extracted.

I don't know your financial status, but a 4 TB disk holds all my music software that I did download or have on CD or other electronic media. And there is stll lots of room. 1 TB costs about 30-something Euros overhere if you buy a good quality drive.

Installing:
There are some files that you have more than once. So far there is a reason that some of PGMusic's programs have their own file access path. Combining these would save you just a couple of giga bytes.

You always should install over the existing installation. That
1. maintains your settings,
2. keeps your extras,
3, saves disk space.

You will need more disk space with each new update. Some of the disk space could be reused when you save your downloaded software after the install onto an external backup drive.

Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build