Top LEft of first screenshot happens when i spawn a car, no matter what server, started randomly during the middle of me playing once and wont go away, i always move my mods away from beam when i load into MP, so only mp is in my mods folder.
Also I get red boxes that say invalid zip for EVERY mod on EVERY server. So mp is basically unplayable now.
First issue might be solved by renaming your userfolder. Go to
C:\Users\O1LER\AppData\Local\BeamNG.drive
then there should be a folder called 0.26. This is your userfolder for the beamNG version 0.26. Rename it to something else, just as a backup.
Then start normal beamNG trough steam. BeamNG will create a new 0.26 folder.
Then close beamNG and start beamMP.
You should now be able to drive on the server again. If there are any car configs or mods that you want to transfer over, you can do it now. Be careful with mods, as its possible that the issue was a mod in the first place.
The second question you had, the small red errors that appear in the top right when joining a server, the are no issue. BeamNG just gets confused when a server provides the same mod as you already had in singleplayer
