This post was put together for your situation. All the links are valid even though some of the diagrams / images no longer display automatically within the text. Just click to access. (You'll see what I mean when you see the linked UHH post.) You mention using LR so it would seem you have the the conversion from RAW to JPEG covered.

You mention two issues: how to post to UHH (a digital-only display) and how to create images for publishing.

Regarding UHH, see the explanation in the link below. Specifically, manage the LR export parameters (or any similar software) to reduce the pixel resolution of the image, and if desired, lower the JPEG quality. You can test the various settings and then create a User Export Preset so you don't have to retest over and over for each new image.

https://www.uglyhedgehog.com/t-512745-1.html

Regarding a high-resolution image for publication, first review any published requirements from your target customer. Otherwise, do not change the pixel resolution nor the JPEG quality and simply convert from the edited RAW to JPEG. This too you can save as a User Export Preset for quick reuse. If different customers have different technical requirements, create specific User Export Presets for each unique set to parameters.