I have purchased a new Panasonic GX80 and take RW2 Raw images.
I use Lightroom version: 5.7  which will not read my RW2 files.
I prefer to shoot raw files.
How do I use the RW2 files in my version of Lightroomj.
Nice camera! I have a GX8 that is similar and like it a lot.
You have two choices. You can download and use Adobe's free DNG converter. The current version will copy your files into an Adobe format that can be used by your software. There is no quality or functional loss.
The second choice is to buy an upgrade to the current version of Lightroom. It can be either the subscription plan or the perpetual license.
Good luck! You have a great camera!
More info on the (no cost) DNG conversion route
The downside is that every time you want to import into Lightroom, you must first convert all your RAW files to DNG format using the converter then edit the DNGs (not the RAW files) in Lightroom 5.7.
Upgrading means you can edit the RAW files in Lightroom 6 or CC (Cloud) with no conversion required. If you do upgrade, ensure that you are running the current version 6.8 (or CC 2015.8 Cloud version) since the camera was first supported in Lightroom 6.6.