Are you using Lightroom Classic or Lightroom Desktop (the cloud version). From your post it sounds like the latter. When you import into Lightroom Desktop (the cloud version), it copies the files to a temporary local folder on your hard drive. It will then start uploading these files to the cloud and (depending on your local storage settings), start deleting the originals from the local hard drive. So you need enough space on your local hard drive to do the import initially.
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Past that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.
Just another Adobe customer; My Sys; APP: LRC 9.4, PS 21.2.1; CMP: WIN WS 16GB OS 10 v1909 (18363), mid 2015 MBPr 15” 16GB MACOS 10.15.6; 4K EXT DSPY; CAM: Canon 5D Mk III, Fuji X-T3