Hi Jeff,
To use Spider V Remote with your Spider V20 on Mac:
Install Spider V Remote v2 for Mac from Line 6.
Connect amp via USB; no extra driver needed.
Edit presets in Signal Flow or Editor and Save Tone → Spider V20.
Backup presets via Save Tone to Disk or import/export .l6p files.
For custom amps/cabs, use the Cloud to import presets, then edit/save.