MAMP Localhost update issues

Trying to update plugins or install anything into wp-content directory while running WordPress locally through MAMP Pro 2.0. Every time I do this I get a FTP credentials request (see screenshot: http://cl.ly/1t1v3X2r1t430h170O3u). Thus I am unable to update anything.

How do I get around this or fix this?

Also if I copy & paste the new plugin folder into the wp-content/plugins folder to replace the old version, it doesn’t update within WP admin.