Hello,
1) I have logged in but once I try to check themes or any other menu item I face a redirect https://gyazo.com/37bb8a0f3f7bdd623d567cdec60945b1
2) You created header using Elementor https://prnt.sc/mkUgecAZKPqv So, our header builder does not work. Remove Elementor headers if you want to use our header builder.
Regards