some add-ons i downloaded, in the add-on screen when i put the cursor above them it shows the description and "Dependecies: ..."
e.g.:
"Doing something nice blahblah.
Dependencies: Sky, Chorus."

all (and only) the add-ons with the dependencies don't work. what to do???

In the game on the addons page are there any Dependencies missing for your addons

Most addons come with their dependencies with a few rare exceptions. Qrikko's threat hud fully admits it is only an interface to KTM and that you need KTM to use it. Other than that, people either clearly explain what you need or they provide it.

Mentioning Sky makes me think you have come Cosmos or Khaos mods on your PC. That's handled from cosmosui.org. Any time an addon appears red, it means it's either out of date (fix by checking load out of date addons) or a dependency is missing. If one is missing, it tells you what is missing. Either turn it on or download what's missing if it's not listed.