ten-th: Is there a date known, when No Man's Sky Origins will be available here at GOG ?
After latest files installation, i can see no new UI Menue like shown in YouTube videos. So i assume, it's not released, yet, here on GOG ...
Start the game and look at the lower right corner, it will show the version that is being launched. If it is 3.01 which is build 64352 that should be the latest available for main. Experimental is a newer build so if you are using Galaxy with betas enabled then you can update to the newest available version which is build 64514.
You might also check the videos to verify what version they were playing and if they were PC or console just to be sure.
As noted above, the offline downloaders were posted last week and a patch to 3.01 is currently available for offline updating or one can redownload the entire game. It typically takes a business day or two before GOG is able to complete their work to make offline installers available.
If using Galaxy you can verify the version by clicking on the box just to the right of the Play button.