My workflow picks file from shared drive (my account has specific credentials assigned)
When loading the workflow to the server I get an error:
Just to check is that a full qualification you have in there? Like if you have a shared drive that everyone knows as "T:" but that's not the real name of that path? I would start there.
The second thing is that while you may have the correct credentials, the profile that the server utilizes may not have access. Usually a service account. Reach out to your admin on that.
Expanding on Treyson's comments.