Video is a year old. You want BepInEx from here[valheim.thunderstore.io], CLLC from here[valheim.thunderstore.io], and if you want the BepInEx config manager you need this one[valheim.thunderstore.io] - the current latest generic release from github does NOT work on the valheim specific BepInEx.

Once you have those in the right place*, which the video shows, you should have:

1. A console window open when you launch valheim, look in here for any red text. If no red that's good, if it shows CLLC loaded even better. If you don't have this window reinstall BepInEx.
   
2. A warning message on the valheim title screen in the lower right about using mods, and a status message in the upper left with BepInEx version and number of running mods. If not reinstall BepInEx.
   
3. If you installed the config manager F1 should open the config manager dialog - you can do this in the title screen, and/or during play.

*(and no lingering wrong files - if necessary as last resort completely delete your valheim folder and reinstall valheim)

That takes care of getting mods up and running. I don't use CLLC, but for your purpose you should be good to go with just changing min & max stars to 0 as CuriosityKillsTheMADCat stated. CLLC doesn't have vanilla default settings, you could also optionally change the item drops option to `vanilla`. There may be other things that could be reverted to vanilla, personally I didn't get that far through using CLLC.