A common issue that can occur with users new to installing WordPress themes is a "Broken theme and/or stylesheets missing” error message being displayed when trying to upload or activate the theme. This error message does not mean that the theme you have purchased is broken, it simply means it has been uploaded incorrectly. Luckily, there is a very easy fix.

The most likely reason for your header and footer settings to not reflect in a page is that the page you are looking at is using a custom header. You can check if a page is using a custom header/footer from here: https://drive.google.com/file/d/1k2UrgaA1kh1mRBYbIE6IGdm4Tmmx-XnS/view?usp=sharing

Custom Header/Footer is assigned when you want a page to have a different header than the regular pages which is controlled via theme options. You can either de-assign the custom header or you can find the custom header block as a static content post type in Static Contents screen. You can then edit the Header/Footer block in the Static Content itself to reflect in that page.