In this case water will be accumulate and eventually will leak out.
This is a common problem where installer doesn't drill the hole with 45 degree downward angle ( it is explained in the manual) so condensation water will free flow to drain.
I also suggest you inspect the drain line and ensure it has a free downward path and ensure that the drain line is not higher than the drain tube.
When evaparator coils get dirty or lack of refrigerent in the compressor ( due to leak), the indoor unit will be iced up and eventually leak water inside.
Therefore the indoor unit filters needs to be cleaned periodically. If the unit is being used very dirty environment it is good idea to calling a HVAC service and have them wash and clean the coils.
After cleaning filters and coils if icing issue still continues unit needs to be leak tested first and recharged properly.