No waiting on the mail. Here is exactly what happens.
The moment you pay
You get a download link on the confirmation screen and a second copy by email. If the email is slow, check spam - and the confirmation page link works either way.
What you receive
For most products, a ZIP file. Unzip it first, then open index.html in your web browser. Most volumes have an index page that links everything together. A few reference titles are PDF files instead.
What you need
A web browser and a way to unzip files (or a PDF reader for the PDF titles). There is no installer and no login. Most volumes work without an internet connection once unzipped; a few load display fonts, icons or an interactive 3D view from the internet.
Keeping it
The files are yours. Back them up, put them on a USB drive, burn them to a disc for the bench. There is no license server to phone home to and nothing that expires.
If something is wrong
Email hoodsfinds@gmail.com and say which product it is. A broken or incomplete download gets fixed - that is the part that matters.