Allowing paypal to bypass password protection in .htaccess

I have a password protected ecommerce site. I am having difficulty with my .htaccess file allowing Paypal to send back the IPN. (I did learn that I needed the site to have SSL - so got that installed.)

Here is what I am using.

#allow access from paypal only
SetEnvIf Referer "^https://www\.paypal\.com" auth_referral
Order Allow,Deny
Deny from all

AuthType Basic
AuthName "FRBSF"
AuthUserFile "/path/to/my/.htpasswds/public_html/passwd"
Require valid-user
Allow from paypal.com
Allow from env=auth_referral
Satisfy any

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I've tried dozens of combinations of code over the past 4 days and I end up with either the password protection not working and PayPal IPN working fine or vice versa. I need them both to work ASAP!

I've also tried using SetEnvIf HOST.

Thanks in advance!