Once you have downloaded and installed the Course Creation and Catalog Add-in you will need to activate SideLoading on the SharePoint Team Site where you installed the Course Creation and Catalog Add-in.
There are two ways you can do that.
A: By using a little Desktop Application we have developed called LMS SLA. Here you just need to have the url of the Team Site and the login details for a Office 365 Global Administrator.
Download: LMS365 SideLoading Activator App
B: The other way is to use PowerShell. If you are happy to use PowerShell then simply download the PS Scripts and execute these.
Download: SideLoading PowerShell Scripts
Here are the instructions:
1: Download and Install the SPO management shell
2: Extract the SideLoadingScripts.zip file
3. Execute EnableSideLoading.ps1 from PowerShell
4: Provide the URL for the site collection where sideloading should be enabled
5: Enter your user credentials. You must be a Tenant Admin to activate this feature
6: Once SideLoading is activated you will be able to create courses