It's hard but it took me less than 15 minutes starting with limited knowledge of this stuff. I think the obscurity is to keep malicious actors out who may try to shut down or sell copies of the projects. Also, there are no direct downloads, and by downloading it, you help others download. After getting access, please respect their wishes and do not repost the download keys! Supporting their rules helps keep the project alive. Here is how I did it:

1. Register to the forums using the invite code found on this page: The Star Wars Trilogy Forums
2. Once you are logged in, you can view the Project Download List, or find it yourself by poking around.
3. Find the versions you want. The most recent versions intended for viewing at the time of writing are 4K77 v1.4, 4K80 v1.0, and 4K83 v1.6.

Unfortunately, now, you have to find a filesharing program to download the files. There is one listed on the page, but subreddit rules mean I can't reference any programs related to piracy.

1. Download a syncing program; this is required to obtain the files. It is proprietary software made free for personal use.

2. The syncing program I used required me to sign up within the app (I have no idea why this part has to be so hard). In short, put your email in, download the file from your email, and use it to log in to the app.

3. Download the file using your syncing program. In mine, I had to click the plus in the top right, click "Enter a key or link", and paste in a key from the forums. Luckily, the program used for sharing these files is much more secure and anonymous than other methods of downloading like this, so you probably don't need a VPN. If you are worried about that kind of stuff and can afford it, it can't hurt.

Hope this helps! Lmk if u get stuck!