Hi @Biz_Account and welcome to the Forum! 
Freelancers who don’t share your Company’s email domain, will be considered as Guests. They will have limited access to the Organization and they can only see what is explicitly shared with them.
- If you share a task with them; they will only see that task. You can also assign a task to a Guest.
- If you share a project with them; they will see that project and all tasks within that project.
- If you invite them to a Team; they will see all public projects within that Team, providing they’ve been added as a team member.
You can find more information about Guests in the following article: https://asana.com/guide/help/organizations/guests
Please let me know if you have any follow-up question. Have a great Tuesday! 