How to add code for a login without using Iframe

trying to add my codre to the page
when I use iframe the vendor I use for client to log into does not allow frames
trying to add my code to the pagey site without iframe?

You can just make up your own custom login and register lightboxes…
https://www.youtube.com/watch?v=QbH8_eudjbE - video for tutorial below…
https://support.totallycodable.com/en/article/create-custom-log-in-sign-on-screen-using-wix-code

… or you can use Wix’s own signup form.
https://support.wix.com/en/article/creating-a-custom-signup-form-for-your-members-area

If you set up your own custom lightboxes, then you need to change your signup settings so that it loads yours up instead of Wix’s own windows still.
https://support.wix.com/en/article/corvid-enabling-custom-site-registration

Api reference for register.
https://www.wix.com/corvid/reference/wix-users.html#register
https://www.wix.com/corvid/reference/wix-users-backend.html#register

Api reference for login.
https://www.wix.com/corvid/reference/wix-users.html#login
https://www.wix.com/corvid/reference/wix-users-backend.html#login

Finally note that if you use your own custom lightboxes, then you can’t use social logins.

If you still need html then have a look at Wix Support pages for it.
https://support.wix.com/en/article/adding-html-code
https://support.wix.com/en/article/guidelines-and-limitations-of-the-html-code-and-embed-a-site-elements
https://support.wix.com/en/article/embedding-an-external-site-3240166
https://support.wix.com/en/article/embedding-custom-code-to-your-site

Also, note that you can pass data to and from a page to a html frame and vice versa using code with on message and post message.
https://www.wix.com/corvid/reference/$w.HtmlComponent.html