Thunderbird Conversations-won't install

Tried installing the Conversation Add-on from a file. Says it cannot install since it has not been verified. I would think Mozilla would have this verified. I am doing something wrong?

I had no problem installing Thunderbird Conversations 2.13.3 in Thunderbird 52.4.0.

It is listed as Works with 45.0-58.

What version of Thunderbird are you using?

Thanks for your reply. I am running 52.4.0 64 bit on Windows 10.