Running a download website is not that complicated, if, you are computer literate. You install files onto your server, and then you upload the files you wish people to download. The system is linked to paypal, so they click on the file they want, they pay, and then either download the file immediately, or receive a download link. The download link enables obscured filenames and limited download time and frequency before it locks. The betters system are pretty trouble free, but sometimes people just can't work out how to download the files, or leave it too long, or select the wrong ones, so you need to keep an eye on the reports the system sends, which notify you of potential issues. So you generate codes on paypal, enter the paypal info on your download site, and then link the money to the files to the clients. If you are happy with this, then fire away. My first system was all drag and drop, but the supplier stopped supporting it, so the paypal system failed when paypal changed their system. I had to then find another - and the current one I use is ok - but much clunkier! I have to enter lots of strings of data manually - in my case, it's track number, price, ID, paypal link, real file name, obscured file name - a real pain if you have lots, but ok to just add new tracks as you produce them. It's reliable and less than £100. It would NOT install on my main server space, and I had to use a US hosting service, even though I'm in the UK.
How this even applies to the new downloading VAT rules, I have no idea - because the customers download the files from the US? It's fine for UK customers, which they all thankfully are, but one day somebody will buy one from the EU. No idea what to do then.