Hi Vladimir,
I can’t seem to see your page properly right now: https://share.getcloudapp.com/Wnuy7mXX
There are multiple 404 issues in your website. Try clearing all caching mechanisms set in your website.
Try rebuilding your permalinks as well: https://www.hostinger.ph/tutorials/wordpress-broken-permalinks
With regards to adding these buttons, you may create a GenerateBlocks Buttons Block and add it to the Header through Appearance > Customize > Widgets > Header: https://share.getcloudapp.com/kpuJ8Az6
You may also create a Block Element and hook it to places like menu_bar_items
or after_primary_menu
as such: https://share.getcloudapp.com/yAuKkNr1
Reference to GB Button Block: https://docs.generateblocks.com/article/buttons-overview/#icon
Hope this clarifies. 🙂