I'd like to offer up my method for managing my stash of textures, elements, overlays, and masks that I've acquired through courses like AWAKE, Kaizen, and from content I've purchased. It's a bit different to what Sebastian Michaels' suggests, but each to their own. It's a big decision to make, so considering various strategies allows you to make an informed decision before taking the plunge to get organized. This overview assumes you already know a bit about navigating your way round Lightroom Classic and how to import images.

Just considering textures alone - I have over 4000 textures after the AWAKE and KAIZEN courses, along with creating my own. Too many to search through if they were all in one folder. One option is to create folders for each type of texture: grunge, paint, black and white, cracks, urban, concrete… but that quickly makes for some hard decisions. How would you file this texture on the right? You certainly don't want to duplicate the image and put it into multiple folders!

Rather than fuss about which folder an image should be filed in, forget about filing entirely. Let Lightroom work for you instead, with keywords, searches, and smart collections. When you get a new content bundle, unzip each content package into a main folder for all your goodies. I usually let the folder be autonamed by the package name, which also makes it easier to trace back to the source (e.g., "2LO Artist 11", "FS_Cloudy_Day_background_"). Within my main folder, I also have separate folders for AWAKE, Kaizen, and my own content, but that doesn't really matter. Once the content is unzipped, import it into your Lightroom catalog. Then (and this is the only painful bit), keyword every image.

How to keyword
Ctrl-K or Cmd-K gets you to the Keywording panel quickly. Simply type in your keywords, separated by commas. As your collection of keywords builds up, Lightroom will autosuggest and autocomplete for you. For the above texture, I've tagged it as "fabric, cracked, watercolor, texture". I can then easily find it (and others) by simply searching for "texture fabric" or "texture watercolor", or whatever. It's up to you as to how detailed you get, but once keyworded, you will more likely be able to find your goodies in the future. Keyword all your photos too, not just your stash. Even if you have a big collection already, start like you mean to go on with new images and knock the rest off in 15 minute chunks each day till they're all done. It will save you more time in the long run as your images will be so much easier to find. I have over 45000 images in my collection, and they are finally all keyworded.