Fusion 360 - managing numerous seats

Each Fusion 360 seat must be assigned to a user.

As an example, if you own 3 seats of Fusion 360, under the Primary Admin user must appear 3 users where each of them must have 1 seat of Fusion 360 assigned.

To assign an user and a Fusion 360 seat respectively, please proceed with the following steps:

https://knowledge.autodesk.com/customer-service/account-management/users-software/user-management/assign-products-to-users 

After you get your users assigned, please proceed to download Fusion 360 install it and activate it by using the intended credentials user that has been assigned before.