1. Download Nougat 7.1.1 Lineage OS for Samsung Galaxy J7
Currently we only have Un-Official ROM developed by Apavayan Sinha, for detailed what's working and not here.
2. Download Nougat Lineage OS Gapps
If you want another more complete package you can choose here
3. Installing Lineage OS on Galaxy J7
How to Install Lineage OS Android 7.1.1 (Nougat) ROM based onto Galaxy J7?
For being able to install Nougat Lineage OS on Galaxy J7 you need to download the required files from above and transfer or save them to your phone’s internal storage.
Then, you need to power off your Samsung Galaxy J7 smartphone
Good; now boot it into TWRP Recovery mode.
Now the first thing you need to do once, you are into TWRP Recovery main menu is to perform a factory / hard reset. From the TWRP main menu tap on the wipe button and select Advanced Wipe. Then select all Dalvik cache, System, Data and Cache options.
Up next, tap on the install option from the TWRP main menu and just pick the Nougat Lineage OS ROM that you’ve downloaded before which is saved to your phone’s internal storage and install it.
Then, Flash the Lineage Gapps file after the ROM installation has finished using the same options as in the last step from above.
Reboot your Samsung Galaxy J7 and enjoy on the Android 7.1.1 Nougat world.