I was having the same issue - not able to add an Equitable account to Mint. But I finally got it to work. Here is what I did:
1. Open Mint and start the process of adding and account
2. Search for Equitable (https://equitable.com)
3. Select the institution and click Link Account
4. Login to the popup Equitable site inside Mint
5. You will then be asked to type your 6-digit code
6. Stop at this point and open another browser window in Incognito/Private mode
7. Login to your Equitable account in that separate window
8. When Equitable sends you a 6-digit code, go back to Mint and enter it in the popup window.
9. Mint should complete the process and add the account.
10. Sequence is everything.
Hope this works for you.
