Active job

Re-seal bathroom - urgent

Bathroom sealant is looking mouldy especially in the corner of the shower (where it drips on to the floor) so we peeled some of it back from the floor tiles and found dirt underneath. We had some sealant ready to go but wanted the opinion of a professional if just sealant will be OK or does it need something else before the sealant? This is urgent for us for someone to look at it tonight or tomorrow as we only have one bathroom and don't want to take showers with part of the floor unsealed. Photo attached. Thanks!