From the Search Console dashboard, select "Manage site," then "Verify this site." If "HTML file upload" is not listed under "Recommended method," it should be listed under the "Alternate method" tab.
When you select this method, you will be asked to download an HTML file. Download it, then upload it to the specified location. Do not make any changes to the content of the file or the filename; the file needs to be kept exactly the same. If it is changed, Search Console will not be able to verify the site.

Check it out here - https://www.hoemyblog.com/2018/11/how-to-use-google-search-console-2018.html