Thanks for your inquiry! The portal that you're referring to above is our UC Endpoint Lab. This lab is "Always On" which means that you can connect to it anytime after your first reservation. You will need to reserve the UC Endpoint lab from the Sandbox Catalog. When you reserve this lab, you'll receive an email that will provide you with the correct VPN credentials to connect to the lab's network.
Using the automation in the lab, you will be able to add several types of devices - shown in this image below:
Keep in mind that this lab is for testing out endpoints and "kicking the tires." If you'd like full administrative access to a collaboration lab you'll need to reserve our 'Collaboration 10.5,' 'Collaboration 11.0' or 'Collaboration Plus' labs.
If you're having difficulty reserving the Sandbox labs, please follow the instructions on this post but supplement the UC Endpoint lab.
DevNet Sandbox Team