The best way to invite team members to Quip is to share a document with them, either by publishing a link or sharing with their email address. You can learn more about how to do that over here: https://quip.com/kGmoAbdWz3pl
You can also add team members to your Quip Business account through your Business Portal, which you can access by visiting admin.quip.com. Learn more about how to add people to your team and more features of Quip's Business Portal over here: https://quip.com/YFPQAMH9O8tr.
As always, if you have any additional questions, please feel free to email firstname.lastname@example.org.