The invitation emails are not sent in this case. When the invited user logs in to his Skyvia account (or signs up, if the users is not yet registered), he can choose whether to use his default account or the account of the user that invited him.
When several users share the same account, this means that they share the same pricing plan subscriptions and resource limitations. For example, if two users share an account with a subscription for the free plan for Query, which has a limit for a five queries per day, after they execute five queries in total (be it 2 for one user and 3 for another or 5 for one user and 0 for another), both users won't be able to execute queries till the next day.
Also, note, a user cannot have access to packages, connections, and stored queries of other users, sharing the same account. This allows limiting access of different users to the company data. However, we will consider to add this functionality and contact you as soon as any results are available.
Please refer to https://skyvia.com/resources/docs/index.html?account_users.htm ("Inviting and Deleting Users from Account" section).
Feel free to ask any further questions.