Once a Organization Admin has invited you to the Formstack Account, an email will be sent asking you to accept.
Brand New FSID User
After accepting the invitation by clicking the button in the email, enter your name and email address, and choose a unique password.
Existing FSID User, New Product
If you're an existing Formstack user but were invited to join a different product, accept the emailed invitation and enter your established Formstack password.
Once logged in you'll be able to view and manage, within your permissions, the new product from your App Stack will show when you click the App Launcher icon.