Taboola is a content advertising platform. In other words, Taboola is a content delivery network that promotes its partner web content through its widget based ads on its partner website. You can use Taboola as a publisher or an advertiser. When you are a publisher, you will be running Taboola widget ads that showcase the content from taboola partner network. When you are an advertiser, you promote your content through Taboola partner website.
Taboola is a big company. It has regional offices in various cities around the world, from New Delhi, India, Bangkok, Thailand, to Sao Paulo, Brazil, Tel Aviv, Israel, London, UK, Los Angles, Chicago, and New York.
I am not using Taboola, either as a publisher or an advertiser. Therefore, I do not know anything about publisher requirements