https://dipakgajjar.com/set-up-ftp-for-wordpress-running-via-mamp/
Sometimes you may need ftp access for your local WordPress development (to update WordPress core version, themes and Plugins) running via MAMP or MAMP PRO. You can use the ftp server built into Mac OS X but unfortunately ftp server is not activated by default. Here are the steps to activate the ftp server and how to setting up FTP access:
(1) Open ‘System Preferences’
(2) Go to ‘Sharing’
(3) Activate “File Sharing”
(4) Click on “Options”
(5) Select (tick) “Share files and folders using SMB”
(6) Click on “Done”
(7) Below the entry “FTP Access: On” you will find a text Other users can access shared folders on this computer, and administrators all volumes, at “afp://10.10.10.10” or “smb://10.10.10.10”. (you will get different IP than 10.10.10.10)
(8) Write down the IP Address (you will get different IP than 10.10.10.10)
NOTE: mine is 10.0.0.18
(9) Close the preferences panel.
Now, open MAMP / MAMP PRO.
(10) Go to ‘General’
(11) Change to your Mac username from ‘www (Apache) / mysql (MySQL)’ in ‘Run Apache/MySQL server as user:’ option.
(12) Restart your webserver (Apache?)
✓ All Done! Now you’re good to access your ftp using following credentials :
FTP Host: Your IP (step 8) or localhost
Username: Your mac username (step 11)
Password: Your mac password
Local Directory Path: Your WordPress installation path ( eg.: /Applications/MAMP/htdocs/wordpress.local )