The first time you use LOCK-IT(ADMIN) it will ask you to set a PASSWORD for the current project. (Each project can have a different password). Also it will ask you for a password hint to help you remember.

After that every time you use LOCK-IT(ADMIN), it will ask for your PASSWORD to LOCK or UNLOCK elements. 

In the main form dialog you can add or remove elements from the LOCK LIST, or you can view which elements are locked.

All the elements in the LOCK LIST will also be protected if you use LOCK-IT(USER).

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin.

You may need to restart the Autodesk product to activate the app/plug-in.

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10) and uninstall as you would any other application from your system.

Some users behind a Firewall or proxy may have problems to activate the addin. Please follow the instruction on the link to solve proxy problems.

https://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/AutoCAD-requests-to-Autodesk-servers-blocked-by-proxy-servers.html