I've just installed this on my nexus because I needed it to temporary replace a failed phone. Some information is missing on the first post so I'll post it here.
Just like official lineageOS, there are no gapps included. So remember to install them from opengapps. Select ARM cpu and android 8.1. Choose the smaller pack.
There is not enough space to run this ROM and pico gapps (the smaller pack). So you need to change the system and cache partitions size. To do that, check lineageOS 16/17 posts on this forum. There is a flashable zip.
Stock TWRP will give an error when you flash this rom. You need a modded TWRP that it's not easy to find.
Check here Also, it's possible that this twrp version will fail to reboot the system. Mine did.
After flashing the ROM and before flashing gapps, you need to resize the partition size and you use twrp for that: Just go to wipe, select system and "change or repair file system". There's an option to repartition. Make sure that the partition size is above 1200mb. Remember to format "cache" partition.
First boot will take 5 minutes. Be patient.
Good luck and have fun!