There are two things you could do in case the invited team member does not respond to your invitation:
Doublecheck whether you have entered the correct email address for the invitation. If not, simply cancel the invitation and re-invite the team member with the correct email address.
Send a reminder to the invited team member. Here’s the step by step guide on how to do it:
Go to the Team menu
Click on the invited team member
Click Send Reminder
An email reminder will be sent to the team member in question.