How to compile?

[sarimarton]

Hi,

When I open the project in XCode and try to build, the following errors appear:

No account for team "LM5Z78756B". Add a new account in the Accounts preference pane or verify that your accounts have valid credentials.
No signing certificate "Mac Development" found: No "Mac Development" signing certificate matching team ID "LM5Z78756B" with a private key was found.

Any advice how to proceed? Thanks.