Installing and Setup the Paypal Module:

1. Login to the Admin panel for Zen Cart.
2. In the navigation menu hover over the Modules options, then click Payment.
3. Click PayPal Express Checkout from the payment modules list, then click the +install button to the right.
   
   The settings for this module will be editable and you will see a message stating "PayPal Express Checkout NOT CONFIGURED YET," select / enter your required settings. Below is a chart that goes over the available options.
   

   Option	Description
   Enable this Payment Module	True enables, this shipping option. If you select False, this shipping option will not be available. It will still be installed, just 'turned off.'
   Sort order of display	The number you enter here will affect where this option will display on the modules list. Zero will be at the top of the list, and higher numbers will be further down the list.
   Payment Zone	If you select a Zone from the drop-down menu, this payment option will only apply to that zone.
   Express Checkout Shortcut Button	Zen Cart states: "The Express Checkout Shortcut button shows up on your shopping cart page to invite your customers to pay using PayPal without having to give all their address details on your site first before selecting shipping options. It has been shown to increase sales and conversions when enabled. Default: On"
   Set Order Status	After customers pay, the status will be set to what you select here.
   Set Unpaid Order Status	Orders made with this module that have not been paid for will be set to what you select here.
   Set Refund Order Status	If an order made with this module is refunded, it will be set to what you select here.
   Express Checkout: Require Confirmed Address	If you want customers that are not logged into your store to confirm their address with paypal, select Yes. Otherwise, leave this set to No to allow purchases from unconfirmed email addresses.
   Express Checkout: Select Cheapest Shipping Automatically	To allow an even faster checkout, you can select Yes to skip the shipping options page, and just automatically select the cheapest shipping option. Select No to let people select their shipping option.
   Express Checkout: Skip Payment Page	Choose Yes if you want to skip the payment page in checkout, and automatically proceed to paypal.
   Express Checkout: Automatic Account Creation	By default, an account is created when a new email address makes a purchase on your website. Select Yes to email the account information to the customer, if you select No they will not be emailed.
   Payment Action	Select Final Sale to process the payment immediately, or Auth Only to put a hold on the account while it is processing the payment.
   Transaction Currency	Choose the currency you want to receive, if a customer pays with a different currency, paypal will convert the money to your selection.
   Store (Brand) Name at Paypal	Enter the store name that you want displayed on the paypal checkout area, leave it blank to display your paypal store name.
   Allow eCheck?	This type of payment is not instant, to allow it anyway select Any, if you do not want to accept it, choose Instant Only.
   Paypal Page Style	To use a Custom Page Style you setup in your paypal account, enter the name here. This is case-sensitive, so be sure to enter it exactly.
   API Signature -- Username	Zen cart advises to enter "The API Username from your PayPal API Signature settings under *API Access*. This value typically looks like an email address and is case-sensitive."
   API Signature -- Password	Zen cart states "The API Password from your PayPal API Signature settings under *API Access*. This value is a 16-character code and is case-sensitive."
   API Signature -- Signature Code	Zen cart advises to enter "The API Signature from your PayPal API Signature settings under *API Access*. This value is a 56-character code, and is case-sensitive."
   Paypal Mode	Choose Paypal to use a regular Paypal account for this option, or choose from Payflow-UK, or Payflow-US to use these options.
   Live or Sandbox	Choose live to accept paypal payments, or sandbox if you do not want to process payments fully, but test the functionality.
   Debug Mode	Debug mode allows you to be notified when transactions do not process successfully. Choose Off to disable this option. To log errors on alerts, select Alerts only, if you want to record all errors to a file select Log File, and to have the errors recorded and emailed to you choose Log and Email.

   After selecting / entering your preferred settings, click the update button, and the Paypal option will be available in your eshop.
   
   Congratulations, now you know how to setup the paypal module in Zen Cart!