Here is a possible solution. I have code on my homepage that checks if the user is logged in and then it automatically pops up a lightbox with the loginbox and a button that they click that takes them to their dashboard. It seems to work pretty well. I have created a custom registration page that submits the user data to the CRM, as well as a database. After the submit the data, it automatically logs them in, as I make the paid plan page the landing page after they submit their data. Also, if they leave the site and come back without logging out, it will take them back to this page. Just a thought to help with this problem until they allow us to select the landing page after the purchase is done. Here is the code on the homepage that should help you.
import wixUsers from ‘wix-users’;
import wixData from ‘wix-data’;
import wixLocation from ‘wix-location’;
import wixWindow from ‘wix-window’;
$w.onReady( function () {
if (wixUsers.currentUser.loggedIn) {
wixWindow.openLightbox(“Login”);
}
})