Hello,
sorry for asking so many questions today.
I tried shading the Orbot, but it looks very dark and no matter what I do the result is approximately the same. I also added lights, but didn't do any difference. 
Hi Roxana,
Check the light strength, the Environment (World) light Strength and the Exposure (Color Managment):
Also, the Albedo (and the Emission) should be set to sRGB.
(A handy trick is, with the Node Wrangler enabled, you can Select the Principled Shader and then press SHIFT+CTRL+T, to get to the Principled Setup; go to the relevant folder and select alll the images you need. The result is what you can see above. It feels a bit like cheating, but it saves a lot of time and everything is set to Non-Color where needed.)
You're also probably expecting the lights to glow, so for that you just have to turn on Bloom in Eevee's render properties. Be aware that the lights need to have the enough intensity for them to start glowing and look like they are turned on. You can also tweak the intensity and threshold values to fine tune the results you want.
Thank you! Didn't know about that trick.
Yes, bloom was turned off.
It looks good now!