That code isn’t merely to log in and logout, that code is for a members own profile page for which the tutorial is here.
https://support.wix.com/en/article/corvid-tutorial-building-your-own-members-area
For this tutorial to work properly you need to have made yourself two dynamic pages as stated in the tutorial as the first page will be read only and the second page will be read and write.
The first page is to show the user their own member profile which you can do as well as using the Wix Members app already.
The first time that the site member will view this page after they have logged into your site, then it will only show what you have captured so far from your signup page.
So, if you have simply used Wix default or custom signup form then that will only must likely be email and first and last name etc, whilst the password will not be shown as it will be saved in the WIx CRM only.
If you make up your own lightboxes for signup and login and use them instead after setting your member signup settings to Corvid, then you can capture what ever you want to on your signup form and then it will be displayed on the first read only dynamic page for the site member.
The second page which is read and write, is where the site member can go to add additional data or change something on the existing data etc, with all this being saved into the Members dataset that you create with this tutorial.
If you use this with your own lightboxes then you are needing to not use the Wix Login bar, so that the only way the user can log in and out is through your members page.
Note that the Wix Login Bar is a closed shop and you can’t do anything with it through code, it is a feature of the Wix Members app that you can’t edit, just like the Wix Members app collection called Members/PrivateMembersData tat gets added automatically when you use the Wix Members app.
I have used this tutorial as starting point for a members only page, so you can change the tutorial to whatever suits your needs.
If you want to get started with your own lightboxes, then simply see Nayeli (Code Queen) great tutorials about it linked below to get you started.
Signup
https://www.totallycodable.com/wix/corvid/custom-registration-for-site-login-using-wix-code
https://www.youtube.com/watch?v=QbH8_eudjbE&feature=player_embedded
Login
https://www.totallycodable.com/wix/corvid/create-custom-log-in-sign-on-screen-using-wix-code
Change Member Signup settings to Corvid
https://support.wix.com/en/article/corvid-enabling-custom-site-registration