You do not need an AdSense account to sign up for Ezoic; however, if a site is not using AdSense they will still need to adhere to Ezoic's ad policies and Google's ad policies.
If a site has a banned or penalized AdSense account, it is unlikely Ezoic will be able to approve the site for using Monetization until the penalty is removed.
If a site doesn’t have an Adsense account before signing up for Ezoic, the quality review team may request additional information. This includes asking if sites if they have applied for AdSense, have another AdSense account, or can share Google Analytics read-only access.
Sites with existing AdSense accounts in good standing with Google policy still may be subject to review to Ezoic's ad policies prior to being approved for Ezoic Monetization features.
Sites with existing AdSense accounts that are able to access Ezoic Monetization features should connect existing AdSense accounts via the Monetization tab inside their Ezoic dashboard. Then, sites should turn on Ezoic Mediation underneath the Ezoic Ad Tester features inside the Monetization tab and ensure AdSense is linked and "on" for mediation. This allows Ezoic to include your existing AdSense account in ad optimization and ad serving.
This increases overall revenue and allows your current AdSense account to remain active and accrue revenue as Ezoic will report any ad earnings that were generated from your current AdSense account in Ezoic, but ad earnings from AdSense alone will still be paid out via your current AdSense account (all ad earnings from Ezoic, and Ezoic partners, will still be paid out via Ezoic).