In order to use Docsify for the Gsuite aliases you need:
1. Create an alias:
If you use Gsuite account, take a look at the article https://support.google.com/a/answer/33327?hl=en
If you use other non-Gsuite providers, such as Outlook, Zoho, Yandex and so on, take a look at the article
2. Add Docsify to your Main account:
- Sign up on Docsify with the main Gmail account though the link https://app.docsify.net/auth/signup
- Install Docsify extension from Google chrome store
- Once you do this you will be able to use Docsify with all emails connected as aliases to your main account.