Power Bi reprot refresh using dataflow

Hi, 
There is a dataflow in a workspace and a report is using its semantic model for the data, now I am owner of the dataflow as I take over that from my client, now the report and semantic model is present in another workspace, the dataflow is present in another workspace

I am owner of dataflow, I am owner of semantic model
I am able to refresh it, I am able to edit it 

My collegue is also able to do it as he have that access on workspace level, 
when it comes to client, if he downloads the report to local and open in power bi desktop and tried to refresh the report, he is facing access issue, it is asking creds  for Power BI dataflow(legacy), and he is not able to login even if he gives the sign in, it shows the current user isn't signed in.

is it an access issue, that he needs access to the datalake which feeds the dataflow, he is admin of that workspace which has the dataflow,
in the workspace which contains the report and semantic model, I am not able to see the manage access settings

please help here in solving this