What does mean "will not load"? When an add-in doesn't load, it usually issues an error message that is shown in the output window. Can you share a screenshot that shows this error?

Here is image:

Ok, thanks. So there is no error message in the output window, which means that the add-in itself is loading correctly. What causes this error here is described in the lower part as Requested feature is not available, meaning that you didn't process the license upgrade to activate the Java add-in.

Please contact support / licensing at RWS and complain that the license code of the Java add-in that you purchased back in January 2023 wasn't properly delivered. Go to https://gateway.sdl.com/CommunityFeedback?flow=gateway and click on Help Activating / Deactivating License.