You are correct, you need the updates to go with your program.  Go to the Updates folder in your Sage 50 Company folder.  The updates should be there.  You can run them from that folder.  

If this does not work, you may have to update your program.  I have not been able to find the updates online from Sage myself. 

Hello , 

Thanks for reaching out! You can find all update downloads here: https://support.na.sage.com

Once there, use the search bar to find "Download January 2018 2nd Tax Update Release 2017" which should be the latest update available for your version that you can download manually.

Warm Regards, 
Erzsi

Please share the direct link.  I cannot seem to find it.