Trouble opening package in Trados Freelance 2014

Hi everyone! I am having an issue with Trados Freelance 2014, perhaps someone can help.

I received a package from an agency I work for. I was able to import and to open it, but not to edit it: I got an error message stating that "The object reference is not set as an instance of object" plus a banner upon the text editor stating that I must check out the project before modifying it (even if the project was not on Groupshare).
The agency then tried moving the project on Groupshare, but I was not able to see it, even though I was properly connected to their server.

Suspecting that the problem depended on the fact that I am using Trados Freelance 2014 while the package was created using Trados 2017, I tried to connect using a new license the agency gave me, but I was not able to activate it (the button "Activate" was grayed out, as if the program did not recognize the activation code).

If someone could help me finding a solution, I'd be really grateful!

Thanks in advance,

Daniela