Switching from Lightroom to Lightroom Classic problem

Hi, I've contacted Adobe multiple times this week but maybe you've got any ideas as well. So I bought a new Macbook this week cause my old one could not update Photoshop and Lightroom any longer. I'm using Lightroom since 2 years now but the storage 1Tb is getting full. So I decided to switch back to Lightroom Classic. I thought the best way to do this is with the Adobe Lightroom Downloader. On my old macbook it finds the library with 870GB files but it says not enough storage found on a brand new 2TB ssd drive. Adobe is figuring that out. I tried it on my new Macbook where I already installed and synced Lightroom but the program than says No library found. I'm really frustrated, I thought switching would take some time, but this is something else...