It is required to make sure that all the necessary configurations were made.
First of all, please check what search engine is selected for your site in default Magento settings.
Go to Stores > Configuration > Catalog > Catalog > C...
If compared we can say that Advanced Search extension is a part of Elastic Search that deals mainly with modifying the autocomplete popup by adding various product attributes to it and making it more user friendly. It also modified the search result page by adding separate tabs for products, categories, CMS and other entities. Read the full answer to learn more details.