Summary of what happened:
There seems to be an issue with installing fsl on M3 Sonoma Macs. After trying the standard install command, the installer got stuck at 100% for more than a day. After using @paulmccarthy 's suggestion to previous threads, I also used the following commands, all of which failed:
/usr/bin/python3 fslinstaller.py
python fslinstaller.py --conda
python3 fslinstaller.py
ERROR occurred during installation!
This command returned an error: /Users/atesfet/fsl/bin/conda env update -n base -f /private/var/folders/10/69cbxfwj65qcfshpfwmhmxw80000gn/T/tmpefic9b5g/fsl-6.0.7.6_macos-M1.yml
Removing failed installation directory /Users/atesfet/fsl
Restoring contents of /Users/atesfet/fsl
FSL installation failed!
Please check the log file - it may contain some more information to help you diagnose the problem: /Users/atesfet/fsl_installation_20231224150800.log