If you have problems which cannot be resolved, post a note here describing your problems.
Please be aware that certain MODs and hacks contains code that is incompatible with PHP 7.0. This is particularly true with MODs/hacks related to BBcodes. If you have installed a MOD/hack that is incompatible with PHP 7.0, you must fix its code before your phpBB installation will work with PHP 7.0. Please contact the author of the MOD/hack; perhaps they have already fixed their code. If not, post a note here and I'll do my best to assist.