Hi all…
After a lot of trail and errors I have solved my issues for now.
The errors I got from the discovery mentioned above was due to issues in the MIB file.
I took the MIB file to some kind of “MIB-file Validator” site online (The Simpleweb - MIB module validation).
It found two faults in the file.
I had no idea how to fix those parts, so i removed them from the MIB-file.
After this everything is working alot better.
Now I’m learning how to add sensors and stuff on my own. But that might be a story for another time…
Thank you to everyone that helped/try to help.