Matjaž,
Please try to install ArchiCAD 13 Hotfix 2 build 3235 which provides the tested version of Artlantis 3 Add-On.
ArchiCAD 13 has got a built in Add-On for Artlantis 2 and Artlantis 3 is able to open v2 files as well.
Regards,
Marton Kiss
Chief Product Officer
GRAPHISOFT