For eOS one can only build from Nougat onward (CM14) - 11 is too old.
I found at least Nougat sources for the LTE version, sometime those also work on the WIFI variant.
https://github.com/SM-T561/local_manifests/blob/nougat/gtel3g.xml
For LSO15.1 there is an early version (testing stage)
https://xdaforums.com/t/unoffical-rom-testing-purpose-only-lineageos-15-1-for-galaxy-tab-e-sm-t560-sm-t561.4619261/