Stripe refers to stripe.com
You should buy an SSL certificate from a good certificate provider. We recommend DigiCert — their certificates have very wide acceptance (and in particular should work well on mobile browsers, where many other certificate providers fall short). NameCheap is another good option. They have slightly lower acceptance but their basic certificates cost $10 to $20 a year.
Setup Stripe.
After getting your Stripe account setup. Go to your Account Settings by clicking your account name in the top right of the Stripe Dashboard page.
From your Account setting, select API Keys. You will have a Secret Key and a Publishable Key listed for testing and a Secret Key and a Publishable Key for a live form.
You will need your Secret Key and Publishable Key for your Donate Plus form. Only use your live keys if you are ready to go live with credit card transactions. "If you do not have an SSL certificate installed to your domain, it is not recomended to go live."
Setup Your Add-on
Once you install your Donate Plus add-on.
Add the block to a page and fill in the information it requests.
Give your form a name.
Add your API keys from your stripe.com account
Give your button a title. e.g. "Give Now"
Enter the text you would like to be seen at the bottom just before the submit button is pressed. e.g. "Double check your order before you Submit"
Enter the text you would like to be seen after a successful "Recurring" credit card transaction. e.g. "Thank you for your Continued support"
Enter the text you would like to be seen after a successful "One Time" credit card transaction. e.g. "Thank you for your support"
You are set!!!
Testing
After adding the Donate Plus form to your page, the form will be ready for testing or excepting transactions if your stripe account is live. For test credit card numbers, refer to: https://stripe.com/docs/testing
For a quick success test, simply use the card number 4242 4242 4242 4242 and any valid expiry date and any CVC number.
I am not support for Stripe.com!! but I will support my add-on.