Hello @Giannis_Kakavoulis,
Sorry for the long delay in answering.
The functionality of Instagram was blocked on the site because of Too Many Requests” error. This problem was passed to our developers, but there is no ready solution for now, unfortunately. Likely functionality of our Instagram widget needs to be rewritten and it will take some time. I hope a solution for the problem will be added in one of the next theme updates.
You can try to use an additional plugin for Instagram on your site, for example, https://wordpress.org/plugins/instagram-feed/
Regards