As always, setting up MAMP on a new computer and I ran into problems again. In this version of MAMP, mod_rewrite is installed and enabled by default (you can see in http://localhost:8888/MAMP/phpinfo.php ), however it still wasn't working for me. I was able to fix it by opening /Applications/MAMP/conf/apache/httpd.conf and changing line 197 from

<Directory />
  Options Indexes FollowSymLinks
  AllowOverride None
</Directory>

to:

<Directory />
  Options Indexes FollowSymLinks
  AllowOverride All
</Directory>

Source: stackoverflow