I have subscribed to the Lightroom and when I tried importing my pictures and videos, I am getting errors while importing videos. It looks like it is unable to read HEIC or HEVC files from iphone. I am using a Mac and it is my understanding that lightroom can read such files on Macs.
The error message is misleading "Could not move a file to the destination folder because it is not writable or ther is not enough free space." There is over 1.3 TB of free space on my network drive.
Are you on a Catalina Mac OS? If so, you have to give read/write permissions to Lightroom so that it can copy files onto the system. Mac can definitely import/read HEIC and HEVC files without any issues.
Go to System Settings-> Security & Privacy -> Full Disk Access -> Add Lightroom. Do the same for 'Files and Folders' and 'Accessibility' section.