The package with the Adamas theme are 26 packs of icons. Icons are used in several modules and sections of theme. In order to get the ability to add icons to the site, you first need to unpack them. Go to "Ultimate" and "Icon Fonts Manager" (p.1 and 2 on image below). To download the new pack of icons, click on "Upload New Icons" (p.3 on image below).
A window will open with two tabs - the download from media library and the download from other sources (p.1 and 2 on image below). Note, that by the default, in media library is already loaded with seven packs of icons by Linea. To download the current pack of icons in the library, click on it. Then click on the button "Insert Fonts Zip File" (p.3 and 4 on image below).
After downloading, you will see a new icon pack loaded. Now you can use these icons for the visual design of the site.
To download external packs with icons that go along with the theme, click on the "Upload New Icons" and then the tab "Upload Files". Further action will be familiar to you. Click on the "Select Files" - so you are using Windows Explorer. Navigate to the package "Adamas_wp_theme" and the folder "Icon packs". It collected 26 packs of icons - download them selectively, and then decompressed for use.