Hi
Please try to conclude if Source system connection from which you are trying to activate the content is working fine.
Also try to activate some other objects like infocube/DSO using the same source system this exercise will lead you to the fact that whether it is a general issue or specific to this DSO based on which the next steps can be determined.
The first error is about export datasource which is automatically generated for DSO's thus I think once you install the DSO this error will be solved.
Ashish