Q: What is the meaning of the notification 'The revised manuscript has been submitted successfully (EE)'?

This is basically an auto-message from the journal acknowledging receipt of your revised submission. The ‘EE’ refers to ‘Executive Editor,’ which would be the title for the Editor-in-Chief (EIC) at this journal. Now, the Associate/Managing Editor (AE/ME), basically the editor who initially handled your manuscript, will have the revised manuscript re-reviewed.  (The notification though bears the EE's title as the final decision is made by them.) If it was a major revision, it will be re-reviewed by all the initial peer reviewers involved. If it was a minor revision, the AE/ME may choose to re-review on their own. If the updated manuscript meets their requirements and standards, the AE/ME should give an accept decision, of course, after conference with the EIC.

In case it indeed is an acceptance, you may wish to prepare yourself for the subsequent stage (from your perspective) of proofing, by going through the following resources.

• What is the minimum number of comments to be included while proofing my paper?
• Can I correct an error in citation at the page proof stage?
• Can I replace an image at the proofing stage before publication?

All the best for the next update!