If you have a free trial version of the Service Provider account, this is based upon the Starter plan, so you are anyway restricted to a single user. You may still add other service provider users or VAs to your account, but these users cannot access any of the following areas:
Products / Clients/Brands
This means that these users would require the username and password of a connected client account. Please therefore keep these credentials safe at all time.
If your Service Provider account is based upon the Business or Enterprise plan, you can also add normal users to your account, such as team members working for your company. If you wish to restrict any user from accessing your ‘My Clients’ page and from logging in to these linked accounts, we recommend that you configure a Department (in Global Settings) that excludes access to the ‘My Clients’ page.