Took some pictures today and tried to import them in lightroom 5. But the ARW raw files from my a68 are not recognised when I try to import. What can I do to keep using Lightroom 5 with my new camera?
No chance. For LR 5 you'll get no support for A68. You need Lightroom 6.4 for ARW files from the A68.
The only alternative is to convert the ARW to DNG with the DNG converter.
You need to upgrade (purchase) Lightroom 6.4/Lightroom CC 2015.4 or later.
You could also use the FREE ADobe DNG converter to convert the RAWs to DNG and then import the DNGs into Lightroom 5.