* Note, these instructions are "as we understand it" and can be used as a resource, but shouldn't be used as the "end all be all" source of truth. For that, you will need to talk to the LMS provider.
To start, you will need to click on Admin Tools --> Manage Extensibility. This will get you to the page where you are going to register your LTI tool.
From here, clicking on LTI Advantage will get us to the page to Register your LTI Tool. This is where you will find the area to add your LTI information from Content Controller.
As a reminder, you can find this information in Content Controller by clicking on Accounts --> Choose your Account --> Click on Advanced --> Click on LTI. I have an example from my dev instance below.
Your Content Controller information will fit into this page that will pop after clicking on Register Tool.
After you save that information, you will get a response from D2L with the LTI information you will want to use back in Content Controller. As an example, check out the screenshot below.
You should be able to get every piece of information but the deployment ID, but don't worry, that is coming.
After saving that information in Content Controller, go back to D2L and click on External Learning Tools --> Click LTI Advantage --> Click New Deployment.
Look at that, your Deployment ID! Copy that away to save in Content Controller. From the Content Controller side of things, you should have everything you need.
Click on View Links --> Add Link.
You should name your link appropriately and add the deeplinking link that you copied from your Content Controller Accounts LTI page. Now comes the good part...
Go to your Course in D2L and click the Existing Course Drop-Down Menu.
Choose the tool that you registered and you should be served with the deep linking window that lists out all of the content that the account has access to.