Labmatrix is a web-based application, and is accessible at the URL https://labmatrix.nci.nih.gov/labmatrix/. Of note, you must use the Firefox web browser, specifically version 45 ESR, in order to access Labmatrix; if you don't have Firefox (or this version) on your computer, you can put in a help desk ticket to have it installed for you. Your login credentials are your central NIH username and password.
Labmatrix Lab Loader
If you are importing clinical labs or cultures, you'll also be using the Labmatrix Lab Loader web application, which lives at https://lmlabs.cancer.gov/; your account information is again the same as your NIH username and password.