Paypal: configure return URL to redirect back to login page

Hello,
I would like to have the return URL in paypal to bring the customers to the login page.

How to do that?
If i put in the return URL ex.:
10.0.0.1/login.html or www.google.hr (this will also redirect them to login page),
then i get a warning message from PayPal when i press on the “Return to merchant link”:
"You are going back to an not secured site…, " (something like this),
i dont want to scare the customers with this warning messages.
So I need to make a secure SSL return URL.

So what should I input?

Thank you

I guess you need to enable SSL and provide SSL authentication.
However free solution is to use non-signed certificate, user browser would alarm about not-signed certificate 100%.
Signed and trusted certificate costs money.

Of course i already have enabled ssl and i have a signed certificate.

The problem is that the return URL brings the customer to the user page, and not to the login page.
And i cannot make a secure ssl connection to the login page.

If I enable under hotspot the HTTPS login and make a https link to the login page it doesnt work,
because i have to put the local ip adress : https://10.0.0.1/login.html the certificate will not work as trusted because i didnt input the public ip. If input the public ip : https://mydomain.com/login.html , then this link doesnt work (because the mikrotik router works i think only with local address when accessing the hotspot page).

Please explain me in detail what should i input to have a secure link back to the login page (no the user page)

Thank you